Reference

OpenSCAD cheat sheet: every shape, function and operator

This OpenSCAD cheat sheet lists every built-in shape, transform, boolean, operator, special variable and function on one page, with the defaults you actually need to remember. It follows the stable 2021.01 release and flags newer development-snapshot features separately. Click any chip to copy it.

11 min read Updated October 2026 All levels OpenSCAD reference · 1 of 8

The five lines you'll type most

Smooth curves: $fa = 1; $fs = 0.4; at the top of the file.
A through-hole: difference() { cube([40, 20, 4]); translate([10, 10, -1]) cylinder(h = 6, d = 3.4); }
A row of copies: for (x = [0 : 10 : 40]) translate([x, 0, 0]) cube(5);
Rounded corners: hull() four cylinders, or offset(r = 3) a 2D shape before extruding.
A 2D shape you can print: linear_extrude(height = 3) square([20, 10]);

Version notes.

Everything here works in the latest stable release, OpenSCAD 2021.01, unless it's tagged with a version or listed under snapshot-only features. Snapshots are the nightly builds and the 2026.10 test builds on openscad.org. PrintPal's browser editor runs a 2025 snapshot with the Manifold engine and roof() switched on. It has no textmetrics() or 3MF import and uses a single built-in font for text().

OpenSCAD syntax basics

Variables, modules, functions, files

x = 10;Assignment. One value per scope: the last one wins

x = cond ? a : b;Conditional value

f = function (x) x * 2;Function literal (2021.01+)

module name(a, b = 2) { … }Define a module (makes geometry)

function name(a) = a * 2;Define a function (returns a value)

name(1, b = 3);Call: positional args first, then named

include <file.scad>Paste the whole file in, including its variables

use <file.scad>Import only its modules and functions

// note /* block */Comments

undef true false PIBuilt-in constants (PI ≈ 3.14159)

OpenSCAD default values worth memorising

What you get when you leave an argument out

Call or variable	Default	Why it matters
`cube()`	size 1, `center = false`	Grows from the origin into +X, +Y, +Z
`sphere()`	`r = 1`	Centred on the origin. Poles are flat, so it's slightly shorter than its diameter
`cylinder()`	`h = 1`, `r1 = r2 = 1`, `center = false`	Positional order is `h, r1, r2, center`
`circle()` / `square()`	`r = 1` / size 1	Squares sit on the origin unless `center = true`
`linear_extrude()`	`height = 100`, `twist = 0`, `scale = 1`	Forget the height and you get a 100 mm tower
`rotate_extrude()`	`angle = 360`, `convexity = 2`	The 2D profile must stay on one side of the Y axis
`text()`	`size = 10`, `font = "Liberation Sans"`, `halign = "left"`, `valign = "baseline"`	Capital letters come out about `size` mm tall
`import("x.svg")`	`dpi = 72`	Applies to unitless SVGs. Pass `dpi = 96` for files drawn at 96 px per inch
`offset()`	`r = 1`	Pass either `r` or `delta`
`polygon()` / `polyhedron()`	`convexity = 1`	Raise it if the preview shows see-through glitches
`$fn`	0 (off)	When above 0, sets an exact segment count and overrides `$fa`/`$fs`
`$fa` / `$fs`	12° / 2 mm	Every segment is at least 12° and at least 2 mm, so small holes get very few sides
Minimum segments	5	With `$fn = 0`, even a tiny circle gets at least 5 sides

OpenSCAD operators

Arithmetic, comparison, logical

Operator	Meaning	Operator	Meaning
`a + b`	Add (element-wise on vectors)	`a < b`	Less than
`a - b`	Subtract	`a <= b`	Less or equal
`a * b`	Multiply (dot product for two vectors)	`a == b`	Equal
`a / b`	Divide	`a != b`	Not equal
`a % b`	Modulo (remainder)	`a >= b`	Greater or equal
`a ^ b`	Power (2021.01+)	`a > b`	Greater than
`a && b`	Logical AND	`a \|\| b`	Logical OR
`!a`	Logical NOT	`c ? a : b`	Conditional

"a" + "b" and undef + 1 give undef with a warning, not a string or a number. Use str("a", "b") to join text.

OpenSCAD special variables ($fn, $fa, $fs, $t)

Dollar variables pass down into every call

Variable	Default	What it controls
`$fn`	0	Exact number of segments for circles, spheres and cylinders when above 0 (minimum 3). The manual advises staying at or below 128.
`$fa`	12	Minimum angle per segment, in degrees. Smaller means smoother big curves.
`$fs`	2	Minimum segment length in mm. Smaller means smoother small curves.
`$t`	0	Animation time. It runs from 0 up to, but never reaching, 1.
`$preview`	n/a	`true` in an F5 preview, `false` in an F6 render or command-line export (2019.05+).
`$children`	n/a	How many children were passed to the current module.
`$vpr` `$vpt` `$vpd`	n/a	Viewport rotation, translation and distance. Read them, or set them to aim the camera.
`$vpf`	n/a	Viewport field of view (2021.01+).
`$parent_modules`	n/a	Depth of the module call stack. Use with `parent_module(i)`.

Segment count when $fn is 0: max(min(360 / $fa, 2πr / $fs), 5), rounded up. With the defaults that's 5 segments for r = 1.5 and 30 for r = 10.

Debug modifier characters

Put one in front of any statement

*Disable: ignore this subtree

!Root: show only this subtree

#Debug: highlight it in preview, still part of the model

%Background: ghosted in preview, left out of the model

The # and % highlights only appear in desktop OpenSCAD's F5 preview. # on a difference() cutter is the fastest way to see where a hole really is.

2D shapes

Flat shapes in the XY plane

Call	Description
`circle(r)` / `circle(d = …)`	Circle centred on the origin
`square(size, center = false)`	Square or rectangle. `size` is a number or `[x, y]`
`polygon(points, paths, convexity)`	Any outline. Optional `paths` cut holes
`text(t, size, font, halign, valign, spacing, direction, language, script)`	Text outline from a font
`import("file.svg")` / `import("file.dxf")`	2D file import. SVG also takes `center` and `dpi`
`projection(cut = false)`	3D to 2D silhouette. `cut = true` slices at z = 0
`offset(r \| delta, chamfer = false)`	Grow or shrink a 2D shape, rounded or sharp

2D shapes need an extrusion before you can print them. See 2D shapes and extrusion.

3D shapes and extrusions

Solid building blocks

Call	Description
`cube(size, center = false)`	Box. `size` is a number or `[x, y, z]`
`sphere(r)` / `sphere(d = …)`	Ball centred on the origin. `d` must be named
`cylinder(h, r \| d, center = false)`	Cylinder standing on z = 0
`cylinder(h, r1, r2)` / `cylinder(h, d1 = …, d2 = …)`	Cone or truncated cone
`polyhedron(points, faces, convexity)`	Any closed solid. Faces list points clockwise seen from outside
`import("file.stl" \| "file.off" \| "file.amf" \| "file.3mf")`	Mesh import (AMF and 3MF since 2019.05)
`surface(file, center, invert, convexity)`	Heightmap from a PNG or DAT file
`linear_extrude(height, center, convexity, twist, slices, scale)`	Push a 2D shape straight up, optionally twisting or tapering
`rotate_extrude(angle = 360, convexity = 2)`	Spin a 2D profile around the Z axis

Details, pitfalls and print-ready hole sizes: 3D primitives reference.

Transformations

Move, rotate, scale, mirror, colour

Call	Description
`translate([x, y, z])`	Move by a vector
`rotate([x, y, z])`	Rotate in degrees about the origin: X first, then Y, then Z
`rotate(a, [x, y, z])`	Rotate `a`° about an axis. `rotate(a)` alone turns around Z
`scale(s)` / `scale([x, y, z])`	Multiply sizes. 1 leaves an axis alone
`resize([x, y, z], auto = false)`	Stretch to an exact size. 0 keeps an axis, `auto = true` scales it to match
`mirror([x, y, z])`	Mirror across the plane through the origin with that normal
`multmatrix(m)`	Apply a 4×4 (or 3×4) transform matrix
`color("name" \| "#rrggbb" \| [r, g, b, a], alpha)`	Preview colour only (hex strings 2019.05+). STL has no colour

Boolean operations, hull and minkowski

Combine shapes

union() { … }Merge children (implicit at top level)

difference() { A(); B(); }First child minus every later child

intersection() { … }Keep only shared volume

hull() { … }Tightest convex skin around the children

minkowski() { … }Grow one child by the shape of the other. Rounds edges, but slow

render(convexity) { … }Fully render a subtree during preview

Why cutters should overshoot and how to keep booleans fast: boolean operations guide.

Lists and vectors

Indexing and vector maths

v = [10, 20, 30];Make a list (any types, can nest)

v[0]10. Indexes start at 0, out of range gives undef

v.x v.y v.zFirst, second, third element

len(v)3. Also works on strings

concat([1, 2], [3])[1, 2, 3]. Lists only, use str() for text

[1, 2] + [3, 4][4, 6], element-wise

[1, 2, 3] * [4, 5, 6]32, the dot product

lookup(2.5, [[0, 0], [5, 10]])5, linear interpolation in a table

List comprehensions

Build lists in one expression

[for (i = [0 : 3]) i * i][0, 1, 4, 9]

[for (i = [1 : 6]) if (i % 2 == 0) i][2, 4, 6], filtered

[for (i = [0 : 3]) if (i % 2 == 0) i else -i][0, -1, 2, -3] (2019.05+)

[for (i = [0 : 2]) let (a = i * 120) [cos(a), sin(a)]]Three points on a unit circle

[0, each [1, 2], 3][0, 1, 2, 3], spliced in (2019.05+)

[for (r = [[1, 2], [3]]) each r][1, 2, 3], flattened one level

[for (i = 0; i < 4; i = i + 1) i][0, 1, 2, 3], C-style (2019.05+)

[for (c = "abc") c]["a", "b", "c"]

Flow control: for, if, let

Repeat, choose, name things

for (i = [0 : 10]) …0 to 10 inclusive, step 1

for (i = [0 : 2 : 10]) …Step 2: 0, 2, … 10

for (i = [10 : -2 : 0]) …Count down with a negative step

for (p = [[0, 0], [5, 5]]) …Loop over a list

for (x = [0 : 2], y = [0 : 2]) …Nested: 9 copies

intersection_for (i = [0 : 2]) …Intersect the copies instead of merging

if (c) { … } else { … }Choose geometry

let (r = 5) { … }Local constants (module form 2019.05+)

assert(h > 0, "h must be positive");Stop with an error (2019.05+)

echo("h =", h);Print to the console

Scoping rules, recursion and when a loop can't do what you want: OpenSCAD language reference.

Type test functions

Check what a value is (2019.05+)

is_undef(x)Is it undef?

is_bool(x)true or false?

is_num(x)A number?

is_string(x)A string?

is_list(x)A list? (false for ranges)

is_function(x)A function literal? (2021.01+)

String and utility functions

Text, search, version, modules

str("M", 3)"M3", joins anything into a string

len("M3x10")5

search("x", "M3x10")[2], index of the match

chr(65) ord("A")"A" and 65 (ord 2019.05+)

version() version_num()[2021, 1, 0] and 20210100 on 2021.01

children() children(i)Draw the shapes passed into a module

parent_module(i)Name of a calling module

rands(min, max, n, seed)List of n random numbers (seed makes it repeatable)

Math functions

Trig in degrees, scalar and vector maths

Trigonometry (degrees)	Numbers	Vectors
`sin(a)` `cos(a)` `tan(a)`	`abs(x)` `sign(x)`	`norm(v)` (length)
`asin(x)` `acos(x)` `atan(x)`	`floor(x)` `ceil(x)` `round(x)`	`cross(a, b)`
`atan2(y, x)`	`ln(x)` natural, `log(x)` base 10, `exp(x)`	`min(v)` `max(v)`
`pow(b, e)` · `sqrt(x)` · `min(a, b, …)` · `max(a, b, …)` · `round(-2.5)` is -3 (halves round away from zero)

Trig functions use degrees, not radians.

sin(30) is 0.5, and atan2(1, 1) returns 45. To pass an angle you have in radians, convert it first: rad * 180 / PI.

What does echo(sin(90)); print in OpenSCAD?

0.893997
1
1.5708
0

90 is read as degrees, and sin(90°) is 1. 0.894 is what you'd get for 90 radians, which is the classic mistake when porting code from Python or JavaScript.

Snapshot-only features (not in 2021.01)

Need a nightly or 2026.10 test build

Feature	What it does
Manifold geometry engine	Much faster renders. Turn it on in Preferences, or pass `--backend=manifold` on the command line
`roof(method = "straight" \| "voronoi")`	Turns a 2D outline into a 45° sloped roof solid
`fill()`	Removes the holes from a 2D shape
`textmetrics()`, `fontmetrics()`	Measure text and fonts as data, for example to size a label plate
`linear_extrude(v = [x, y, z], segments = n)`	Extrude along a direction vector, with extra segments
`rotate_extrude(start = a)`	Start angle for a partial sweep
`text(em = …)`	Size text by the font's em square instead of `size`
`import("file.obj")`	OBJ mesh import
`&` `\|` `~` `<<` `>>`	Bitwise operators on integers

In some snapshots these sit behind experimental switches under Preferences → Features. Code that uses them won't parse or run in 2021.01.

Copy-paste OpenSCAD examples

Rounded plate with minkowski()

// 40 × 30 × 4 mm plate with 3 mm round corners
minkowski() {
  cube([34, 24, 3]);                  // 40 - 2×3, 30 - 2×3, 4 - 1
  cylinder(r = 3, h = 1, $fn = 32);
}

Hollow tube with a 2 mm wall

difference() {
  cylinder(h = 40, d = 20, $fn = 64);
  translate([0, 0, -1])
    cylinder(h = 42, d = 16, $fn = 64);
}

Staggered hex studs

for (x = [0 : 10 : 50], y = [0 : 10 : 40])
  translate([x, y + (x / 10 % 2 == 1 ? 5 : 0), 0])
    cylinder(h = 3, d = 8, $fn = 6);

Solid vase blank with rotate_extrude()

// Print it in vase (spiral) mode
rotate_extrude($fn = 120)
  polygon([[0, 0], [20, 0], [15, 20], [25, 50], [12, 60], [0, 60]]);

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Frequently asked questions

Is there an official OpenSCAD cheat sheet?

Yes. openscad.org/cheatsheet is the official one-page reference, and each entry links to the OpenSCAD User Manual on Wikibooks. This page covers the same built-ins and adds defaults, version notes, worked examples and common pitfalls.

Does OpenSCAD use degrees or radians?

Degrees. sin(90) is 1, rotate([0, 0, 45]) turns 45°, and inverse functions such as atan2(1, 1) return degrees (45). If you have an angle in radians, multiply it by 180 / PI before passing it in.

What are the default $fn, $fa and $fs values in OpenSCAD?

$fn = 0 (off), $fa = 12 degrees and $fs = 2 mm. With those defaults every circle gets at least 5 segments, so a 3 mm hole is a pentagon. Setting $fa = 1 and $fs = 0.4 gives print-quality curves, and a 3 mm hole then gets 24 segments.

What is the difference between include and use in OpenSCAD?

include <file.scad> works as if you pasted the file in: its modules, functions, variables and any top-level geometry all come along. use <file.scad> imports only modules and functions and ignores the file's top-level code. BOSL2 asks for include <BOSL2/std.scad>.

OpenSCAD tutorial for beginners OpenSCAD language reference OpenSCAD 3D primitives 2D shapes and extrusion OpenSCAD transformations OpenSCAD libraries (BOSL2, MCAD)

Tools for thisAll tools

CAD AgentDescribe a part in plain English and get editable OpenSCAD with a live 3D preview and STL or 3MF export.

Watch it doneVideo library

0:57 Parametric CAD from a photo using PrintPalTools

0:25 turn text to mechanical parts for 3D printingTools

2:12 CAD Agent, but the Prompts DoubleIdeas

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