The engine understands exactly four easing shapes. Every Figma easing preset is resolved to one of them at export time, so the runtime stays small and deterministic.

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The four shapes

linear

Constant rate. No acceleration.

hold

A step. Keep the value until the next keyframe — no tween.

cubicBezier

A cubic-bézier curve p = [x1, y1, x2, y2]. Solved per frame with Newton–Raphson and a bisection fallback. y may exceed 0..1 for overshoot / anticipation.

spring

A damped physical spring. bounce runs 0 (no overshoot) → 1 (very bouncy).

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Segment convention

A keyframe’s easing governs interpolation from that keyframe to the next — out-interpolation, like CSS transition-timing-function. So you set the curve on the keyframe you’re leaving:
The last keyframe’s easing is ignored. Before the first key and after the last, the value is held.

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How Figma presets map

The converter resolves every Figma MotionEasing to one of the four shapes:
Springs are a perceptual bounce approximation (ζ = 1 − bounce), not a re-solve of Figma’s physical mass / stiffness / damping. The motion reads the same; the exact overshoot can differ slightly. See Figma Motion coverage.