Slow In / Slow Out Mastery

The Physics Principle

Objects in the real world don't move at constant speeds—they accelerate from rest and decelerate to stops. Slow in/slow out (also called ease in/ease out) captures this fundamental truth. Without it, animation looks mechanical. With it, motion feels alive.

Core Theory

Slow Out (Ease Out): More drawings clustered at the start of a movement. The object accelerates away from its starting position gradually.

Slow In (Ease In): More drawings clustered at the end of a movement. The object decelerates into its final position gradually.

Linear motion: Equal spacing between positions. Rare in nature, useful for mechanical elements or stylistic choice.

The Spacing Principle

Traditional animators controlled this through drawing spacing:

• Tight spacing = slow movement (drawings close together)
• Wide spacing = fast movement (drawings far apart)