Player collision capsule

The player collision capsule is the invisible shape that stands in for the player in the physics world: a cylinder with rounded ends. The character model you see is drawn on top of it, but walls, floors, stairs and doorways only ever touch the capsule. Unity describes its Character Controller as "simply a capsule shaped" collider that moves under script control (Unity Manual: Character Controller component reference).

For artists, the capsule's dimensions matter even though the capsule itself is invisible. They decide how wide a door must be, how high a step can be, and whether a ramp in your rock kit is walkable.

#Properties of the capsule shape

The rounded bottom slides over small bumps and up stairs instead of catching on every edge, and the rounded sides slide along walls. The shape also has limits: Unity notes that its controller "will not be able to climb up walls due to the capsule shape" (Unity Manual: Character Controller component reference).

The capsule is usually bigger than the character. The Level Design Book stresses that player collision sizes "are usually much bigger than the actual character model", a "bigger thicker size" chosen "for more stable movement. It's not a hitbox" (The Level Design Book: Metrics). The camera sits inside it, and "in-game eye height is usually below where actual eyes would be" (The Level Design Book: Metrics).

A capsule with labelled radius and height, a short line marking eye height inside it, and a dashed outline for skin width; beside it a small step labelled step height and a ramp with its slope angle marked. — The capsule's own size (radius, height, skin width) plus the two movement limits that matter most to environment art: step height and walkable slope.Diagram by the handbook author

#Capsule settings in each engine

	Unity (Character Controller)	Unreal (Character)	Godot (CharacterBody3D)
Typical player size	1.0 × 1.8 m (or 1.0 × 2.0 m) (The Level Design Book); Unity's step guidance assumes a 2 m human (Unity Manual)	60 × 176 cm, half-height 88	Set by the collision shape you add
Step limit	Step Offset; 0.1–0.4 m for a 2 m human (Unity Manual)	Max Step Height, "Maximum height character can step up" (Unreal Engine Python API documentation)	Handled by the movement code; `floor_snap_length` 0.1 m keeps the body on slopes (Godot Engine)
Slope limit	Slope Limit, in degrees (Unity Manual)	Walkable Floor Angle (Unreal Engine Python API documentation)	`floor_max_angle`, default 45° (Godot Engine)
Contact margin	Skin Width, ideally 10% of the radius (Unity Manual)	—	`safe_margin`, default 0.001 (Godot Engine)

Unreal measures its capsule by half-height, from the centre to the top, so a 176 cm tall capsule has a half-height of 88 (The Level Design Book: Metrics). Unreal also has a Perch Radius Threshold, which stops the character perching on an edge "if the contact is this close to the edge of the capsule" (Unreal Engine Python API documentation: unreal.CharacterMovementComponent): one reason narrow ledges in a kit may not hold the player.

Unity warns that Step Offset "should not be greater than the Character Controller's height or it will generate an error", and that a Skin Width that is too small is the usual cause of a character getting stuck; keep it "at least greater than 0.01 and more than 10% of the Radius" (Unity Manual: Character Controller component reference).

Different viewsShould the capsule match real human sizes?

Bigger than real, on purpose. The Level Design Book's view is that collision sizes are larger than the model for stable movement, and that eye height sits lower than real eyes (The Level Design Book: Metrics).

Close to real, as a starting point. Unity's guidance frames its step advice around "a 2 meter sized human" (Unity Manual: Character Controller component reference). Starting from real proportions keeps doors and furniture close to real dimensions, which matters in realistic settings.

In practice: the capsule's width and step height are design choices made by the gameplay team. Artists should get the final numbers early, write them into the metrics sheet, and test every kit in a gym. Changing the capsule late breaks every doorway built for the old one.

collision meshes · convex hull · grids and metrics · gym levels and metrics maps · scale and proportion · units, scale and axes

#Further reading and watching

The Level Design Book: Metrics

player sizes in Unity, Unreal and Quake-family engines, and why the collision box is not a hitbox. Beginner, free.

WebBeginnerFree

Unity Manual: Character Controller

slope limit, step offset and skin width explained with practical tips. Beginner, free.

DocsBeginnerFree

Godot: CharacterBody3D class reference

floor angle, snapping and safe margin defaults. Intermediate, free.

WebIntermediateFree

Unreal Engine: CharacterMovementComponent (Python API)

every movement property with a one-line description. Intermediate, free.

DocsIntermediateFree

References

Unity Technologies · Character Controller component reference · Unity Manual, 2026 · docs · accessed 2026-10-21

The Level Design Book · Metrics · The Level Design Book · web · accessed 2026-10-21

Epic Games · unreal.CharacterMovementComponent · Unreal Engine Python API documentation, 2026 · docs · accessed 2026-10-21

Godot Engine contributors · CharacterBody3D (class reference source) · Godot Engine (GitHub), 2026 · docs · accessed 2026-10-21