Rigging & animation · Intermediate

Interpolation

How software fills in the values between two keyframes

What is interpolation in animation?

Interpolation is how animation software fills in the values between two keyframes. The interpolation type sets the path: constant holds a value then jumps, linear moves at a steady speed, and Bezier eases smoothly in and out. Changing the type changes the feel without adding keys.

Think of it like this

Like joining dots on a page: you can hop between them, rule straight lines, or draw a smooth curve, and each gives a different picture.

Where it fits in a 3D project

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

Animate: Making things move over time.

TimeKeyframeSoftware fills the in-between
Keyframes set the key values; interpolation draws the motion between them.

How interpolation works

  1. 01You set keyframes at two or more points in time.
  2. 02Each key carries an interpolation type for the stretch that follows it.
  3. 03On every in-between frame, the software calculates a value from that type.
  4. 04You switch types per key to make motion snap, glide or ease.

Interpolation vs tweening

PropertyInterpolationTweening
What it isThe math that fills the gapMaking the in-between frames
Comes fromMathematics and computer graphicsHand-drawn animation studios
You controlThe type: constant, linear, BezierThe in-between poses themselves

Both describe the same job: tweening is the animator’s word for making in-betweens, and interpolation is the method software uses to compute them.

Where interpolation is used

  • Smooth, organic motion with Bezier
  • Steady, mechanical motion with linear
  • Stepped, pose-to-pose blocking with constant

Beginner tip

Block a new shot with constant interpolation so each pose holds until the next. It shows your timing honestly before smooth curves hide problems. Switch to Bezier once the poses work.

Terms related to interpolation

Interpolation FAQ

Linear vs Bezier interpolation: which should I use?
Use Bezier for most natural motion, because it eases into and out of each key. Use linear for steady, machine-like moves such as a spinning fan or a conveyor belt, where any slowing down would look wrong.
What is constant interpolation?
A type where the value holds still until the next keyframe, then jumps. Animators use it while blocking, and it gives a stepped, stop-motion look on purpose.
Is interpolation the same as AI frame interpolation?
They are related but different. Animation interpolation computes values between keyframes you set. AI frame interpolation invents whole new video frames between existing ones to make playback smoother.

Updated October 29, 2026 · Browse all 3D terms