Modeling · Beginner

Bounding box

The smallest box that fully contains a 3D object

Also called Bounds, AABB

What is a bounding box in 3D?

A bounding box is the smallest rectangular box that completely encloses a 3D object. Software uses it as a fast stand-in for the real shape: to measure size, check whether objects might touch, frame the camera, and skip drawing things off screen. It stays invisible unless you turn it on.

Think of it like this

It is the shipping carton that fits snugly around an oddly shaped gift. You learn its size at a glance without studying the gift inside.

Where it fits in a 3D project

  1. Create
  2. Surface
  3. Rig
  4. Animate
  5. Render
  6. Export

Create: Building the shape: modeling, sculpting, scanning or generating it.

How a bounding box works

  1. 01The software finds the lowest and highest point of the object on each axis.
  2. 02Those six values define the corners of a box.
  3. 03Quick checks run against the box first, because a box is cheap to test.
  4. 04Only when two boxes overlap does it check the detailed shapes.

Bounding box vs collision mesh

PropertyBounding boxCollision mesh
ShapeOne simple boxA simplified custom mesh
FitLoose on round or angled objectsClose to the real shape
Made byCalculated automaticallyBuilt or generated per object
Used forSize, culling and first checksPhysics contact in games

Use the bounding box for quick sizing and first-pass checks; give an object a collision mesh when physics needs to follow its real shape.

Where a bounding box is used

  • Reading an object’s real-world size
  • Skipping off-screen objects to speed up rendering
  • Fast first checks for collisions and selection
  • Checking a model fits a 3D printer’s build volume

Beginner tip

Check the bounding box size after importing. If a model looks tiny or huge, its dimensions tell you at once whether the units or scale are wrong.

Terms related to a bounding box

Bounding box FAQ

What is an axis-aligned bounding box?
A bounding box whose sides line up with the world X, Y and Z axes, often shortened to AABB. It is the fastest kind to test, but it fits more loosely when the object is rotated.
How do I show the bounding box in Blender?
Select the object, open Object Properties, and under Viewport Display tick Bounds, with Box as the shape. The sidebar’s Dimensions field, opened with N, gives the same box as width, depth and height.
Why is my bounding box bigger than my model?
Usually a stray vertex sits far from the model, or hidden parts are counted with it. Rotation can also loosen an axis-aligned box. Select all in Edit Mode to find the stray geometry.

Updated October 29, 2026 · Browse all 3D terms