Placeholders and Expressions

OrcaSlicer fills in placeholders when it expands custom G-code and the file name template.

Write a placeholder inside curly braces, for example {layer_num}. Every print, filament and printer setting is a placeholder, with its config key as the name. This page lists the other placeholders, which OrcaSlicer sets while it slices.

• Placeholders by G-code Field
• Reading the Tables
• Expressions and Functions
• Common Errors
• Filaments, Extruders and Nozzles
• Temperatures
• Dimensions
• Print Statistics
• Objects
• Plates
• Presets
• Timestamps
• Environment
• Toolhead Position
• Placeholders for Specific G-code
  • Layer Placeholders
  • Filament Start and End G-code
  • Layer Change G-code
  • Timelapse and Clumping Detection G-code
  • Change Filament G-code
  • Change Extrusion Role G-code
  • Extrusion Roles
• File Name Template
• Examples

Tip

To find the key of a setting, hover over its label in OrcaSlicer, or read the Variable line in the setting's wiki page.

Placeholders by G-code Field

Every custom G-code field can use all settings and the placeholders in Filaments, Extruders and Nozzles, Temperatures, Dimensions, Print Statistics, Objects, Plates, Presets, Timestamps, Environment and Toolhead Position. Some fields also have the extra placeholders in this table.

Field	Key	Extra placeholders
File header G-code	file_start_gcode	None
Start G-code (printer)	machine_start_gcode	None
Start G-code (filament)	filament_start_gcode	Layer Placeholders and Filament Start and End G-code
Before layer change G-code	before_layer_change_gcode	Layer Placeholders
Layer change G-code	layer_change_gcode	Layer Placeholders and Layer Change G-code
Timelapse G-code	time_lapse_gcode	Layer Placeholders and Timelapse and Clumping Detection G-code
Clumping detection G-code	wrapping_detection_gcode	Layer Placeholders, most_used_physical_extruder_id and curr_physical_extruder_id
Change filament G-code	change_filament_gcode	Layer Placeholders and Change Filament G-code
Change extrusion role G-code	change_extrusion_role_gcode filament_change_extrusion_role_gcode process_change_extrusion_role_gcode	filament_change_extrusion_role_gcode and process_change_extrusion_role_gcode added in 2.4.0. Change Extrusion Role G-code
Pause G-code	machine_pause_gcode	None
IDEX/IQEX Mode G-codes	imex_mode_gcodes	Added in 2.5.0. None. It runs before the printer start G-code. Errors in it are shown under the name imex_mode_gcode.
Custom G-code	template_custom_gcode	None
Between Object G-code	printing_by_object_gcode	None
End G-code (filament)	filament_end_gcode	Layer Placeholders and Filament Start and End G-code
End G-code (printer)	machine_end_gcode	Layer Placeholders and the filament values in Filament Start and End G-code
File name template	filename_format	A different set: all settings, and the placeholders marked Also works in the file name. See File Name Template.

machine_pause_gcode has no extra placeholders. The old color_change_extruder placeholder is no longer set, and using it fails.

Reading the Tables

• The Type column gives the unit of each value, for example float (mm). Counts, text and booleans have no unit.
• [] after a name marks a list, for example a list with one value per filament. To pick one value, see Expressions and Functions.
• For a filament, extruder or nozzle index, the Type column says which of the three it is. Many older names say extruder when they mean a filament, for example current_extruder, previous_extruder and is_extruder_used. Check the Type column.
  • Filament index: the position in the filament list, counting from 0.
  • Extruder index: the physical extruder or toolhead, counting from 0, as in current_extruder_id. filament_map[] gives the extruder of each filament.
  • Nozzle index: the nozzle. It is the same as the extruder index unless the printer has several nozzles per extruder.
• Type 1 and Type 2 prime tower are the two values of the Wipe tower type setting. Type 1 is the Bambu Lab style prime tower. Bambu Lab printers always use Type 1.

Expressions and Functions

Inside { }, OrcaSlicer evaluates a small expression language. Placeholder names are case sensitive. Use parentheses to group parts of an expression.

The following operators are available:

• Arithmetic +, -, *, / and % (remainder). For example, {filament_diameter[0] / 2} is the radius of the first filament.
• Comparison ==, !=, <, >, <= and >=. The result is a boolean.
• Logical and / &&, or / || and not / !.
• Conditional condition ? a : b, which gives a when condition is true and b when it is false.
• Text joining with +, for example {"v" + layer_num}.
• Regular-expression match text =~ /pattern/, which is true when the whole text matches the pattern, and !~, which is true when it does not match. To find a part of the text, put .* before and after the pattern, for example {if printer_notes =~ /.*BAMBU.*/}bambu{endif}.

The following functions are available:

Function	Description
int(x)	x without its decimal part. {int(13.9)} is 13.
round(x) floor(x) ceil(x)	x rounded to the nearest, lower or higher whole number.
min(a, b) max(a, b)	The smaller or larger of two numbers.
digits(value, width [, decimals])	value aligned right in width characters, with an optional fixed number of decimals.
zdigits(value, width [, decimals])	Like digits, but padded with leading zeros. {zdigits(5, 4)} is 0005.
random(a, b)	A random number between a and b.
interpolate_table(x, (x0, y0), (x1, y1), ...)	The y value for x on the straight lines between the given points. The x values must increase, and x must be between the first and the last x value.
one_of(value, a, b, ...)	True when the text value is equal to one of the listed texts. A listed value can be a /regex/ pattern, which must match the whole text. value must be text, not a number.
regex_replace(text, /pattern/, replacement)	Added in 2.5.0. text with every match of /pattern/ replaced by replacement. The replacement can use capture groups ($1, $2, ...).
size(list) empty(list)	The number of values in a list, and whether the list is empty.
is_nil(name)	True when the value is not set, for example a filament override that is left empty. For a list, give an index.
filament_change(n)	From this point in the custom G-code, a list of decimal numbers without an index gives the value for filament n.

{if}, {elsif}, {else} and {endif} choose between blocks of text, for example {if layer_num == 0}first{else}later{endif}.

You can store values in variables. {local name = "part"}{name} defines a variable and then prints it. A {local} variable exists only in the custom G-code where it is defined. A {global} variable is also available in the custom G-code that runs later in the same print. A variable can also hold a list. {local temps = (200, 210)} makes a list of two values, and {local zeros = repeat(4, 0)} makes a list of four zeros.

To pick one value from a list, give its index, counting from 0. For example, {nozzle_temperature[1]} is the value for the second filament. Inside { }, a list of decimal numbers without an index gives the value for the current filament. A list of integers, booleans, text or points without an index fails with "Referencing a vector variable when scalar is expected".

OrcaSlicer also accepts an older syntax, [name], which prints one placeholder and does not support expressions. Booleans print as true or false inside { }, and as 1 or 0 inside [ ].

Common Errors

When a placeholder in custom G-code fails, the G-code export fails. The message starts with "Failed to generate G-code for invalid custom G-code." For each field that failed, it gives the key of the field and the first error in that field. An error in filename_format starts with "Processing of the filename_format template failed." instead.

Error	Cause
Not a variable name (inside { }) or Variable does not exist (inside [ ])	The name is misspelled, the field does not have this placeholder (see Placeholders by G-code Field), or your version of OrcaSlicer does not have it yet. In filename_format, only settings and the placeholders marked Also works in the file name exist, see File Name Template.
Referencing a vector variable when scalar is expected	A list of integers, booleans, text or points is used without an index. Add an index, for example {nozzle_temperature[0]}.
This value is known only after the G-code is generated. It can be printed, but not used in a calculation or a comparison.	A value marked Filled in after generation is used in a calculation. See Print Statistics.

Filaments, Extruders and Nozzles

Placeholder	Type	Description
current_extruder current_filament_id	int (filament index)	current_filament_id added in 2.5.0. Filament printing now. The two names usually give the same value. In the printer end G-code, and in the first filament start G-code on Bambu Lab printers, current_filament_id can be different. See Filament Start and End G-code.
current_extruder_id	int (extruder index)	Added in 2.5.0. Extruder printing now. In change_filament_gcode it is still the outgoing extruder.
current_nozzle_id	int (nozzle index)	Added in 2.5.0. Nozzle printing now.
current_hotend	int	Added in 2.4.0. On most printers, the extruder printing now. On Bambu Lab printers, the hotend-rack nozzle when the print moves filaments between nozzles, and -1 otherwise.
has_single_extruder_multi_material_priming	bool	true when the single-extruder multi-material priming area is used.
initial_extruder initial_tool initial_filament_id	int (filament index)	initial_filament_id added in 2.5.0. First filament used in the print. All three names give the same value. initial_extruder and initial_tool also work in the file name.
initial_nozzle_id	int (nozzle index)	Added in 2.5.0. Nozzle of the first filament.
initial_no_support_extruder initial_no_support_tool initial_no_support_filament_id	int (filament index)	initial_no_support_filament_id added in 2.5.0. First filament that is not a support filament. initial_no_support_extruder also works in the file name.
initial_no_support_hotend	int	Added in 2.4.0. Hotend of that filament, with the same rule as current_hotend.
is_extruder_used[]	bool per filament	true for each filament that the print uses.
filament_map[]	int per filament (extruder index + 1)	Extruder of each filament, counting from 1. In change_filament_gcode, filament_map[next_extruder] - 1 is the incoming extruder. Also works in the file name.
first_tools[] first_filaments[]	int per extruder (filament index)	First filament that each extruder prints, or -1. Correct on Bambu Lab and IDEX/IQEX printers. On other printers with several extruders, the values are currently wrong.
first_non_support_tools[] first_non_support_filaments[] first_non_support_hotend[]	int per extruder	first_non_support_hotend added in 2.5.0. Like first_tools[], but without support filaments. first_non_support_hotend[] gives the hotend of that filament instead, with the same rule as current_hotend. The same limitation applies.
num_extruders	int	Number of physical extruders on the printer, also when the print uses fewer. Also works in the file name.
nozzle_diameter_at_nozzle_id[] nozzle_volume_types[]	float (mm) string	Added in 2.5.0. Diameter and flow type of each nozzle. On printers with one nozzle per extruder, there is one value per extruder.
flush_temperatures[] flush_volumetric_speeds[]	int (°C) float (mm³/s)	Purge temperature and purge speed of each filament.
retraction_distance_when_cut	float (mm)	Retraction distance when the filament is cut by the AMS or a filament cutter, for the current filament.
long_retraction_when_cut	bool	true when Long retraction when cut is on for the current filament.
retraction_distance_when_ec long_retraction_when_ec	float (mm) bool	The same two values for an extruder change.
is_all_bbl_filament has_tpu_in_first_layer enable_high_low_temp_mix hold_chamber_temp_for_flat_print max_additional_fan during_print_exhaust_fan_speed_num[]	various	Values used by the Bambu Lab start G-code.

Temperatures

Placeholder	Type	Description
bed_temperature[]	int per filament (°C)	Bed temperature of each filament for the current plate type.
bed_temperature_initial_layer[] first_layer_bed_temperature[]	int per filament (°C)	First-layer bed temperature of each filament for the current plate type.
bed_temperature_initial_layer_single	int (°C)	First-layer bed temperature of the filament that prints first (initial_extruder). If the bed temperature formula is set to the highest temperature, it is the highest first-layer bed temperature of the filaments used on the first layer.
first_layer_temperature[]	int per filament (°C)	First-layer nozzle temperature of each filament.
chamber_temperature[]	int per filament (°C)	Chamber temperature of each filament. Also works in the file name.
chamber_minimal_temperature[]	int per filament (°C)	Added in 2.4.1. Minimum chamber temperature of each filament. Also works in the file name.
overall_chamber_temperature	int (°C)	Highest chamber_temperature[] of the filaments used.
min_vitrification_temperature	int (°C)	Lowest softening temperature of the filaments used.

Dimensions

Placeholder	Type	Description
first_layer_print_convex_hull	array of [x, y] pairs (mm)	Convex hull of the first layer, as a polygon.
first_layer_print_min	float[2] (mm)	Smallest X and Y of the first layer.
first_layer_print_max	float[2] (mm)	Largest X and Y of the first layer.
first_layer_print_size	float[2] (mm)	Width and depth of the first layer.
first_layer_center_no_wipe_tower	float[2] (mm)	Center of the objects on the first layer, including their brim. Only the first copy of each object counts. The prime tower and the skirt are not included.
in_head_wrap_detect_zone	bool	true when the objects, seen from above, or the first layer touch the head-wrap detection area.
first_layer_height	float (mm)	Height of the first layer.
print_bed_min	float[2] (mm)	Smallest X and Y of the bed.
print_bed_max	float[2] (mm)	Largest X and Y of the bed.
print_bed_size	float[2] (mm)	Width and depth of the bed.
max_print_z	int (mm)	Height of the tallest object, rounded up.
max_print_height	int (mm)	Maximum print height of the printer.
adaptive_bed_mesh_min adaptive_bed_mesh_max	float[2] (mm)	Corners of the area to probe. See Adaptive Bed Mesh.
bed_mesh_probe_count bed_mesh_algo	int[2] string	Number of probe points and interpolation algorithm for that area.
has_wipe_tower	bool	true when the print has a prime tower.
wipe_tower_wait_pos_x wipe_tower_wait_pos_y	float (mm)	Added in 2.5.0. A point just outside the prime tower, where the nozzle can wait while it heats. wipe_tower_center_pos_x and wipe_tower_center_pos_y hold the same values under the names Bambu Studio uses.
wipe_tower_wait_pos_valid	bool	Added in 2.5.0. true when the print has a prime tower and the point above is set. wipe_tower_center_pos_valid holds the same value under the name Bambu Studio uses.

Print Statistics

Important

NEW FEATURE: Print statistics in custom G-code Available in: 2.5.0-beta and nightly builds. In 2.5.0-alpha and older, print_time, normal_print_time, silent_print_time, used_filament, total_weight, total_cost, total_wipe_tower_cost and total_wipe_tower_filament work only in the file name. In custom G-code, they stop slicing with "Not a variable name". The error for calculations is also new in 2.5.0-beta. Older versions give a wrong result or a different error.

Some of these values are marked Filled in after generation. OrcaSlicer knows them only after the whole G-code is generated. In custom G-code, it first writes a marker, and replaces the marker with the value at the end. In custom G-code, these values have two decimal places. In the file name, they can have more digits.

Because the value is not known yet, you can print it and join it to text, but you cannot calculate with it:

Works	Fails
{total_weight}	{total_weight * 2}
{"Weight: " + total_weight + " g"}	{total_weight + 5}
{local w = total_weight}{w}	{if total_weight > 100}heavy{endif}
	{int(total_weight)}

An expression in the Fails column stops slicing with "This value is known only after the G-code is generated. It can be printed, but not used in a calculation or a comparison." The same error comes from functions such as round(), min() and one_of(), from regular-expression matches, and from a copy of the value in a variable.

OrcaSlicer reads + from left to right, and text joined with a number stays text. So {"W: " + total_weight + 5} prints W: 123.455 for a weight of 123.45 g. It does not add 5.

Placeholder	Type	Description
normal_print_time print_time	string	Estimated print time in normal mode, written like 2d3h15m, 2h15m, 5m30s or 45s. Times of one hour or more are rounded to the minute. Filled in after generation. Also works in the file name.
silent_print_time	string	Estimated print time in silent mode, in the same format. 0s unless the G-code flavor is Marlin and Silent Mode is on. Filled in after generation. Also works in the file name.
print_time_total_sec	float (s)	Added in 2.5.0. Estimated print time in normal mode, in seconds. Filled in after generation.
print_time_day print_time_hour print_time_minute print_time_sec	int (d) int (h) int (min) int (s)	print_time_day, print_time_hour and print_time_minute added in 2.5.0. Days, hours, minutes and seconds of the normal-mode print time. print_time_sec is only the seconds, not the total. Filled in after generation.
total_layer_count	int	Number of layers.
total_toolchanges	int	Number of filament changes in the print. The filament selected at print start does not count. With a prime tower, this is the prime tower's count. Without one, OrcaSlicer counts the changes in the planned tool order. It is 0 when printing by object without a prime tower. Also works in the file name.
printing_filament_types	string	Only in nightly builds. Filament types that the plate prints with, without duplicates, in the order of the filament list, joined with _. For example ABS_PLA. Also works in the file name.
used_filament used_filament_length	float (m)	Length of filament that the whole print uses. Filled in after generation. used_filament also works in the file name.
extruded_volume[]	float per filament (mm³)	Volume extruded so far with each filament. In custom G-code, this is a running total, so it is 0 in the start G-code. extruded_volume also works in the file name, as the total volume.
extruded_volume_total	float (mm³)	Sum of extruded_volume[]. Also a running total. Also works in the file name, as the total of the whole print.
extruded_weight[]	float per filament (g)	Weight extruded so far with each filament, from the filament density. Also a running total.
extruded_weight_total	float (g)	Sum of extruded_weight[]. Also a running total. For the weight of the whole print, use total_weight. Also works in the file name, as the total of the whole print.
total_weight	float (g)	Filament weight of the whole print. Filled in after generation. Also works in the file name.
total_cost	float (currency)	Filament cost plus the printer's time cost (time_cost per hour of printing). Filled in after generation. Also works in the file name.
total_wipe_tower_cost	float (currency)	Filament cost of the prime tower. Filled in after generation. It is currently 0 with the Type 1 prime tower. Also works in the file name.
total_wipe_tower_filament	float (mm)	Length of filament used for the prime tower. Filled in after generation. It is currently 0 with the Type 1 prime tower. Also works in the file name.

Objects

Placeholder	Type	Description
num_objects	int	Number of objects on the plate. Copies of an object count in num_instances. Also works in the file name.
num_instances	int	Number of printed instances of all objects. Also works in the file name.
current_object_idx	int	Position of the object printing now in the print order, counting from 0. Each copy of an object counts. It changes only when printing by object.
scale[]	string per object	Scale of each object as text, for example x:100% y:50% z:100%. Also works in the file name.
input_filename_base	string	Name of the first printable object, without the extension. If the object has no name, the name of its source file. Also works in the file name, where it is the project name for a saved project.
input_filename	string	input_filename_base followed by .gcode. Also works in the file name.
first_object_name	string	Added in 2.4.2. Name of the first printable object on the plate. Also works in the file name.

Plates

Placeholder	Type	Description
plate_name	string	Name of the plate. Also works in the file name.
plate_number	string	Number of the plate, counting from 1 and padded to two digits, for example 01. Also works in the file name.
model_name	string	Model name saved in the 3MF project, or empty. Also works in the file name.
imex_mode	string	Added in 2.5.0. Name of the plate's IDEX/IQEX parallel mode, or primary in Primary mode. Empty when the printer is not an IDEX/IQEX printer.
imex_mode_index	int	Added in 2.5.0. Index of that mode in the printer's imex_mode_names, counting from 0. This is its row in the Modes grid. 0 is Primary.
imex_mode_gcode	string	Added in 2.5.0. The Mode G-code of that mode, before its placeholders are filled in.

Presets

Placeholder	Type	Description
print_preset	string	Name of the print preset. Also works in the file name.
filament_preset[]	string per filament	Name of the preset of each filament. Also works in the file name.
filament_type[]	string per filament	Material type of each filament, for example PLA or PETG. Also works in the file name.
printer_preset	string	Name of the printer preset. Also works in the file name.

Timestamps

Placeholder	Type	Description
timestamp	string (yyyyMMdd-hhmmss)	Local time when G-code export started. Also works in the file name, as the time when the name is built.
year month day	int	Date of timestamp. Also works in the file name.
hour minute second	int	Time of day of timestamp. Also works in the file name.

Environment

Placeholder	Type	Description
user	string	User name from the USER or USERNAME environment variable, or unknown. Also works in the file name.
version	string	OrcaSlicer version. Also works in the file name.

Toolhead Position

These values describe the toolhead when a custom G-code starts. Only zhop is read-only. If your G-code moves the toolhead, update position[], and OrcaSlicer continues from the new position.

e_position[] and e_retracted[] are correct, and OrcaSlicer reads back your changes, only when Single Extruder Multi Material is off. This setting is on by default. When it is on, do not use these two values.

Placeholder	Type	Description
zhop	float (mm)	Z-hop height when the custom G-code starts. Read-only.
position[]	float[3] (mm)	X, Y and Z position of the toolhead when the custom G-code starts.
e_position[]	float per filament (mm)	Position of the extruder axis. Used only when the G-code uses absolute E distances.
e_retracted[]	float per filament (mm)	How far the filament is retracted when the custom G-code starts.
e_restart_extra[]	float per filament (mm)	Extra length to extrude after the next unretraction.

Placeholders for Specific G-code

OrcaSlicer sets the placeholders in this section only in the G-code that each section names. Placeholders by G-code Field lists them by field.

Important

NEW FEATURE: Placeholders on every path Available in: 2.5.0-beta and nightly builds. In 2.5.0-alpha and older, these placeholders are missing, and using one stops slicing with "Not a variable name":

• max_layer_z in layer_change_gcode.
• layer_num, layer_z and max_layer_z in filament start G-code run by the Type 1 prime tower, and max_layer_z and filament_extruder_id in its filament end G-code.
• layer_z and max_layer_z in the first filament start G-code on Bambu Lab printers.
• The Layer Change G-code placeholders on the brim layers of belt printers.
• The timelapse placeholders other than the layer placeholders, except on Bambu Lab printers, printers with several extruders, and bed slingers outside spiral vase mode.

Layer Placeholders

These placeholders are available in before layer change, layer change, timelapse, clumping detection, change filament, filament start, filament end and printer end G-code.

Placeholder	Type	Description
layer_num	int	Current layer, counting from 0. -1 before the first layer, for example in the call of change_filament_gcode at print start. before_layer_change_gcode and layer_change_gcode get the same number, for the layer that is about to print.
layer_z	float (mm)	Height of the top of the current layer. In filament start, filament end and printer end G-code, the current height of the nozzle. With the Type 1 prime tower, filament start and end G-code get the height of the prime tower layer instead.
max_layer_z	float (mm)	Height of the highest layer printed so far.

Filament Start and End G-code

Placeholder	Type	Description
filament_extruder_id	int	In filament_start_gcode, the filament that is loaded. In filament_end_gcode, the filament that is unloaded. At a tool change without the Type 1 prime tower, filament_end_gcode gets the extruder of that filament instead. Not set in change_filament_gcode.
current_filament_id current_nozzle_id	int (filament index) int (nozzle index)	Added in 2.5.0. Filament and nozzle that the G-code runs for. Set for most calls, including calls from the Type 1 prime tower.
retraction_distance_when_cut long_retraction_when_cut	float (mm) bool	In filament_start_gcode, the values for the filament that is loaded. See Filaments, Extruders and Nozzles.

The filament start G-code for the first filament runs before the first layer, so layer_num is -1 there. On Bambu Lab printers, this filament start G-code runs right after the printer start G-code, for the first filament that is not a support filament.

At the end of the print, filament_end_gcode runs once for each filament in the filament list, and then machine_end_gcode runs. With single extruder multi-material, it runs only for the current filament. machine_end_gcode gets the filament_extruder_id, current_filament_id, current_extruder_id and current_nozzle_id of the last of those calls. This is not always the filament that printed last.

Layer Change G-code

layer_change_gcode also has these placeholders:

Placeholder	Type	Description
current_filament_id current_nozzle_id	int (filament index) int (nozzle index)	Added in 2.5.0. Filament and nozzle printing when the layer starts.
most_used_physical_extruder_id	int	Physical extruder that is used on the most layers of the print. It has the same value on every layer.
previous_layer_mass curr_accumulated_mass	float (g)	Added in 2.5.0. Weight of the previous layer, and weight of everything printed so far. For printers that limit the Y acceleration by the weight on the bed. With a prime tower, the weight includes the filament of the whole prime tower. curr_layer_mass holds the same value as previous_layer_mass under the name Bambu Studio uses.
curr_y_acceleration_limit	float (mm/s²)	Added in 2.5.0. Y acceleration allowed for that weight.

Timelapse and Clumping Detection G-code

Placeholder	Type	Description
most_used_physical_extruder_id	int	Physical extruder that is used on the most layers of the print. Available in time_lapse_gcode and wrapping_detection_gcode.
curr_physical_extruder_id	int	Physical extruder that is active when the G-code runs. Available in time_lapse_gcode and wrapping_detection_gcode.
timelapse_pos_x timelapse_pos_y	int (mm)	X and Y position chosen for the snapshot, rounded to whole millimeters. Only in time_lapse_gcode.
has_timelapse_safe_pos	bool	true when a safe snapshot position was found. Only in time_lapse_gcode.
timelapse_inline_photo	bool	Added in 2.5.0. true when the snapshot is taken without moving to a chosen position. Only in time_lapse_gcode.
farthest_point_timelapse_enabled	bool	Added in 2.5.0. true when the farthest-point timelapse is on for this layer. Only in time_lapse_gcode.
clear_to_x0	bool	Added in 2.5.0. true when the nozzle can travel to X = 0 without crossing the print. Only in time_lapse_gcode.

Change Filament G-code

These placeholders are set in change_filament_gcode.

On most printers that are not Bambu Lab printers, change_filament_gcode also runs once at the start of the print, when the first filament is selected. This call does not happen on Bambu Lab printers or when the print uses only the first filament. In that call, layer_num is -1 and toolchange_count is 1. previous_extruder, current_filament_id and current_hotend are -1, unless the printer start G-code selects a tool with a T command. To skip that call, test layer_num >= 0.

With Enable tower interface features turned on, a tool change at a prime tower interface layer uses the interface print temperature for the incoming filament. In change_filament_gcode, new_filament_temp and the incoming filament's value in temperature[] and first_layer_temperature[] are that temperature. With the Type 2 prime tower, the same is true for nozzle_temperature[] and nozzle_temperature_initial_layer[], and for these values in filament_start_gcode.

Placeholder	Type	Description
previous_extruder next_extruder	int (filament index)	Filament that is unloaded, and filament that is loaded.
current_filament_id next_filament_id	int (filament index)	Added in 2.5.0. The same values as previous_extruder / next_extruder.
current_hotend next_hotend	int	Added in 2.4.0. On most printers, the outgoing and incoming extruder. On Bambu Lab printers, the hotend-rack nozzle when the print moves filaments between nozzles, and -1 otherwise.
current_nozzle_id next_nozzle_id	int (nozzle index)	Added in 2.5.0. Outgoing and incoming nozzle.
old_extruder_variant new_extruder_variant	string	Added in 2.5.0. Extruder variant of the outgoing and incoming extruder, for example Direct Drive Standard.
toolchange_z	float (mm)	Print height of the layer where the change happens. With the Type 1 prime tower, the height of the prime tower layer. It does not include the Z-hop.
outer_wall_volumetric_speed	float (mm³/s)	Outer wall volumetric speed of the new filament, limited to its maximum volumetric speed.
relative_e_axis	bool	true when OrcaSlicer uses relative E distances.
toolchange_count	int	Number of tool changes so far, including this one. When change_filament_gcode runs at print start, that call counts as 1, so the first real change is 2 and the last one is total_toolchanges + 1. Without that call, for example on Bambu Lab printers, the first real change is 1.
fan_speed	int	Old placeholder, kept so that old G-code still works. Always 0.
filament_retract_length_nc	float (mm)	Added in 2.5.0. Nozzle-change retraction length of the outgoing filament, or 0 if there is none.
new_extruder_retracted_length	float (mm)	Added in 2.5.0. How far the filament in the incoming extruder is retracted now.
old_retract_length new_retract_length	float (mm)	Retraction length of the outgoing and incoming filament.
old_retract_length_toolchange new_retract_length_toolchange	float (mm)	Tool change retraction length of the outgoing and incoming filament.
old_filament_temp new_filament_temp	int (°C)	Nozzle temperature of the outgoing and incoming filament.
old_filament_e_feedrate new_filament_e_feedrate	int (mm/min)	Extrusion feedrate of the outgoing and incoming filament, from its volumetric speed limit.
x_after_toolchange y_after_toolchange z_after_toolchange	float (mm)	The nozzle position before the change, or the start point on the Type 1 prime tower. Changing them has no effect. To tell OrcaSlicer that the nozzle moved, update position[].
first_flush_volume second_flush_volume	float (mm of filament)	First and second half of the planned purge length.
flush_length	float (mm of filament)	Total purge length for the tool change.
flush_length_1 … flush_length_4	float (mm of filament)	Parts of the purge. Unused parts are 0.
wipe_avoid_perimeter	bool	true when the travel avoids the prime tower for this change. Only set by the Type 1 prime tower, and false otherwise.
wipe_avoid_pos_x	float (mm)	X position of the line that the travel avoids around the prime tower. Only used by the Type 1 prime tower.
is_prime_tower_interface	bool	With the Type 1 prime tower, true when this change prints a prime tower interface layer.
filament_tower_interface_purge_volume filament_tower_interface_print_temp	float (mm of filament) int (°C)	Interface purge length and interface print temperature of the new filament.
filament_cooling_before_tower[]	float per filament (°C)	Added in 2.4.0. How much the temperature drops before the nozzle enters the prime tower. Only set by the Type 1 prime tower, and 0 on the first layer and on interface layers.
wipe_tower_wait_pos_x wipe_tower_wait_pos_y wipe_tower_wait_pos_valid	float (mm) float (mm) bool	Added in 2.5.0. The same point as in Dimensions. With the Type 1 prime tower, the point is next to where this tool change starts. Bambu Studio's names, wipe_tower_center_pos_x, wipe_tower_center_pos_y and wipe_tower_center_pos_valid, hold the same values.
travel_point_1_x travel_point_1_y	float (mm)	First point of the travel path that the Bambu Lab filament cutter uses. Fixed default values on other printers.
travel_point_2_x travel_point_2_y	float (mm)	Second point of that travel path.
travel_point_3_x travel_point_3_y	float (mm)	Third point of that travel path.

Change Extrusion Role G-code

These placeholders are available in change_extrusion_role_gcode, filament_change_extrusion_role_gcode and process_change_extrusion_role_gcode.

Placeholder	Type	Description
extrusion_role	string	The extrusion role that OrcaSlicer is about to print, for example Perimeter.
last_extrusion_role	string	The previous extrusion role.
layer_num	int	Current layer, counting from 1 in this G-code.
layer_z	float (mm)	Height of the current layer.

Extrusion Roles

extrusion_role and last_extrusion_role have one of these values. Compare them as text, for example {if extrusion_role == "Perimeter"}...{endif}.

Value	Description
Perimeter	Inner wall.
ExternalPerimeter	Outer wall.
OverhangPerimeter	Overhang wall.
InternalInfill	Sparse infill.
SolidInfill	Internal solid infill.
TopSolidInfill	Top surface.
BottomSurface	Bottom surface.
Ironing	Ironing.
BridgeInfill	Bridge, including internal bridges.
GapFill	Gap infill.
Skirt	Skirt.
Brim	Brim.
SupportMaterial	Support.
SupportMaterialInterface	Support interface.
SupportTransition	Support transition.
WipeTower	Prime tower.
Mixed	Several roles, or any other role.

File Name Template

The file name template, filename_format, has its own set of placeholders. It can use all settings, and the placeholders marked Also works in the file name in the tables above. Any other placeholder makes the file name fail with "Processing of the filename_format template failed."

In the file name:

• Print statistics are always the final values. If the name is needed before the G-code exists, OrcaSlicer fills them in after export.
• extruded_volume, extruded_volume_total and extruded_weight_total are totals for the whole print. extruded_volume is one value, not a list.
• extruded_volume_total, extruded_weight_total and initial_extruder work since 2.4.0, and initial_no_support_extruder works since 2.5.0.

These placeholders work only in the file name:

Placeholder	Type	Description
filament_name	string	Added in 2.4.0. Preset name of the lowest-numbered filament that the plate uses, cut at @.
num_filaments	int	Number of extruders. It is the same as num_extruders.

Examples

Start Macro with Temperatures

In the printer start G-code, pass the first-layer temperatures to a Klipper macro. first_layer_temperature[] has one value per filament, so the index initial_extruder picks the filament that prints first.

PRINT_START BED={bed_temperature_initial_layer_single} EXTRUDER={first_layer_temperature[initial_extruder]}

Layer Progress

In the layer change G-code, show the layer on the printer screen. layer_num counts from 0, so add 1.

M117 Layer {layer_num + 1} of {total_layer_count}

Real Tool Changes Only

In the change filament G-code, skip the call at print start. layer_num is -1 before the first layer.

{if layer_num >= 0}
; From filament {previous_extruder + 1} to filament {next_extruder + 1}
M109 S{new_filament_temp}
{endif}

Settings for One Extrusion Role

In the change extrusion role G-code, use a lower acceleration for outer walls.

{if extrusion_role == "ExternalPerimeter"}
M204 S1000
{else}
M204 S3000
{endif}

Value from a Table

Choose a purge length from the nozzle diameter, and store it in a variable. This example uses relative E distances.

{local purge = interpolate_table(nozzle_diameter[0], (0.2, 10), (0.4, 20), (0.8, 40))}
G1 E{purge} F300

Print Summary in the File Header

In the file header G-code, write the print time and the filament use. This works in 2.5.0-beta and newer, see Print Statistics.

; Print time: {print_time}
; Filament: {used_filament} m, {total_weight} g

File Name

This is the default file name template. To add the plate number, add _plate{plate_number} before .gcode. To name every filament type of a multi-material print, not only the first, use {printing_filament_types} instead of {filament_type[initial_tool]}.

{input_filename_base}_{filament_type[initial_tool]}_{print_time}.gcode