Tweening in Animation: Definition & Uses

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Published: August 7, 2025

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What is Tweening in animation? Definition & Meaning

Tweening in animation is the process of creating frames between two main drawings to make movement look smooth. The word “tween” comes from “in-between.” Animators use it to connect key poses so things move naturally on screen. Tweening works differently in hand-drawn animation, digital 2D animation, and 3D animation, but the goal is the same: smooth motion.

Tweening in Hand-Drawn Animation

In traditional cel animation, artists drew each frame by hand. The lead animator drew the key poses, and in-betweeners filled in the drawings between them. This system, which started in the 1920s, helped big studios make animated films faster.

Here’s a good video from Disney artist and animator John Pomeroy, showing how inbetweens are done by hand.

To line up drawings, artists used a light table so they could see the drawings underneath. They often drew on “twos,” which means each drawing stayed on screen for two frames. That added up to 12 drawings per second.

Fast motion sometimes needed a new drawing for every frame (“ones”). Slow motion could use fewer drawings. All of it depended on tweening to keep the action smooth.

Tweening in Digital 2D Animation

Vector animation in Adobe After Effects Example — Here, I’ve imported and rigged a vector character in After Effects. Because it’s vector, I can manipulate the curves and shapes without loss of quality. The ‘crosses’ you see on the line below for the ‘position’ line below are keyframes set to “ease-in” and “ease-out”. This makes the movement a bit slower as the motion approaches the set keyframes, making it more natural and smooth.

Digital 2D animation uses software to create in-between frames automatically. You pick two keyframes, and the software fills in the motion between them. This is called interpolation. It saves time and still looks good, especially on vector animation.

Programs like Adobe Animate, After Effects, Toon Boom Harmony, and Synfig all have tweening tools. You can move, rotate, and stretch shapes without drawing every frame by hand.

There are a few main types of tweening:

Motion Tweening – Moves something smoothly from one spot to another.
Shape Tweening – Changes one shape into another across frames.
Easing – Slows down or speeds up the motion at the start or end to make it feel more natural.

Tweening is used in explainer videos, web design, and cartoons. It helps small teams and individuals (like myself, who do explainer videos for clients) work faster and still create clean, flowing animation.

Tweening in 3D Animation

Control rig in Unreal Engine Echoes of Love 08 04 2025 1 — *You can use the ‘control rig’ in Unreal Engine to set keyframes and animate characters.*

In 3D animation, tweening happens when the computer fills in frames between poses in 3D space. You set key poses, and the program creates the motion between them. This works for things like character movement, camera angles, or rotating objects.

Here’s a video that shows how tweening works in Unreal Engine, using curves.

Check out my work-in-progress animated cyberpunk short film Echoes of Love, which I make in Unreal Engine.

Like 2D software, 3D software like Blender, Maya, Unreal Engine, and 3ds Max lets you choose how the motion works. Note, these options are also available in 2D applications and are not unique to 3D software:

Stepped – No tweening. The pose holds until the next one. Used in rough drafts.
Spline/Bezier – Smooth motion with curves. This is the most common.
Linear – Even motion with no slow-in or slow-out.

You use a tool called a Graph Editor to change how things move. They can bend the motion curve to make a jump slower at the start and faster in the air. That way, the tweened motion doesn’t feel robotic or stiff.

AI-based tools like Cascadeur take animation made in, for example, Unreal Engine, and make it look even more natural:

This video shows the inbetweens among a series of keyframes in Cascadeur.

Frame Timing in Tweening

The number of drawings per second affects how smooth the animation looks. Animating on twos uses 12 drawings per second. Animating on ones uses 24. Fast action needs more in-betweens. Slow movement needs fewer. Tweening makes all of this possible by filling in the frames that keep motion smooth.

Why Tweening Matters

Without tweening, animation would look choppy. Whether it’s drawn by hand, done on a computer, or created in 3D space, tweening is what makes movement feel smooth and, in the end, real(istic). It saves time and lets you control how characters and objects move between poses.

Summing Up

Tweening connects keyframes to create smooth motion. It works differently in hand-drawn, 2D, and 3D animation, but it’s always part of the process. If you want your animation to look clean and controlled, you need tweening.

Read Next: Want to explore the full range of animation styles and techniques?

Start with our Complete Guide to Animation Styles and Techniques — from traditional hand-drawn to motion capture and CGI workflows.

Or browse all animation articles for practical tutorials, creative tools, and deep dives into both 2D and 3D processes.