Ease In vs. Ease Out Keyframes in After Effects

In Adobe After Effects, understanding the difference between ease-in and ease-out keyframes is essential for creating smooth, natural motion. While default linear keyframes move objects at a rigid, robotic speed, easing mimics real-world physics by adjusting acceleration. The fundamental difference lies in the direction of the transition: Ease In slows down a layer as it arrives at a keyframe, while Ease Out speeds up a layer as it departs from a keyframe.

What Is Ease In?

Ease In applies deceleration to an animation. When you apply Ease In to a keyframe, the object moves at full speed toward that point and gradually slows to a stop or transitions smoothly as it enters the keyframe.

• Physical Real-World Equivalent: A car gradually pressing the brakes to come to a halt at a red light.
• Best Used For: The final keyframe of an animation or any point where an element needs to settle softly into its resting position.
• Keyboard Shortcut: Shift + F9 (Windows and Mac).
• Keyframe Icon: An arrow-like shape pointing to the right into the keyframe, indicating incoming deceleration.

What Is Ease Out?

Ease Out applies acceleration to an animation. When you apply Ease Out to a keyframe, the object begins from a stationary or slow state and gradually builds up speed as it leaves the keyframe.

• Physical Real-World Equivalent: A runner bursting out of the starting blocks, building momentum from a standstill.
• Best Used For: The first keyframe of an animation or any point where an element needs to smoothly transition out of a resting state into rapid motion.
• Keyboard Shortcut: Ctrl + Shift + F9 (Windows) or Cmd + Shift + F9 (Mac).
• Keyframe Icon: An arrow-like shape pointing to the left away from the keyframe, indicating outgoing acceleration.

How to Remember the Difference

A common point of confusion is the naming convention, as people often associate "in" with starting and "out" with leaving. In After Effects, the terminology refers to entering and exiting the keyframe itself, not the overall composition:

• Ease In: Easing into the keyframe (arriving).
• Ease Out: Easing out of the keyframe (leaving).

What About Easy Ease?

When working with intermediate keyframes where an object needs to slow down as it approaches the point and gently accelerate as it leaves, you use Easy Ease (Shortcut: F9). Easy Ease combines both Ease In and Ease Out, creating a symmetrical transition that decelerates into the keyframe and accelerates out of it.

Fine-Tuning in the Graph Editor

While keyboard shortcuts apply basic easing curves, opening the Graph Editor allows you to customize the influence and velocity of your Ease In and Ease Out keyframes. In the Speed Graph:

• Ease In displays a curve that slopes downward to zero velocity at the keyframe mark.
• Ease Out displays a curve that starts at zero velocity and curves upward into the motion.

Adjusting the bezier handles in the Graph Editor gives you total control over the intensity of the ease, allowing for dramatic snaps, bounces, or cinematic slow-downs.