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EasingClassic eases

easeInOutQuad

It is slow at both ends and fast in the middle. A mild, even curve: a clear ease without drama.

easeInOutQuad reaches 50% of its travel at 50% of the time and 90% at 78%. Its peak speed is 2x the average.

Classic easesfamily: quadpeak 2x

Progress against time0100.51progress50%90%
The dashed line is linear. The dots mark 50% and 90% of the travel.
Velocity, in multiples of average speed0100.51speed, x average
The dashed line is 1x, the speed of linear.

Live demo

The blue box uses the exact linear() string below, in your browser. The grey box is linear.

easeInOutQuad
linear

Your system asks for reduced motion, so the boxes rest at the end of the move.

Numbers

50% of travel
50%of the time
90% of travel
78%of the time
After 10% of time
2%of the travel is done
Peak speed
2xtimes the average
Overshoot
0%stays inside the end
Undershoot
0%never below the start
linear() points
41at a 0.002 tolerance
cubic-bezier
closeworst gap 0.6 points

Copy the code

css linear() (exact)
animation-timing-function: linear(0, 0.0013, 0.005, 0.0113, 0.02, 0.0313, 0.045, 0.0612, 0.08, 0.1013, 0.125, 0.1513, 0.18, 0.2113, 0.245, 0.2813, 0.32, 0.3612, 0.405, 0.4513, 0.5, 0.5488, 0.595, 0.6387, 0.68, 0.7188, 0.755, 0.7888, 0.82, 0.8488, 0.875, 0.8988, 0.92, 0.9388, 0.955, 0.9688, 0.98, 0.9888, 0.995, 0.9988, 1);
cubic-bezier (nearest fit)
animation-timing-function: cubic-bezier(0.46, 0.02, 0.55, 1);

Least-squares fit to the easeInOutQuad curve; the worst gap is 0.6 points of travel. It is close, not exact: use linear() when the end of the curve matters.

web animations api
el.animate({ translate: ['0 0', '240px 0'] }, { duration: 600, easing: 'linear(0, 0.0013, 0.005, 0.0113, 0.02, 0.0313, 0.045, 0.0612, 0.08, 0.1013, 0.125, 0.1513, 0.18, 0.2113, 0.245, 0.2813, 0.32, 0.3612, 0.405, 0.4513, 0.5, 0.5488, 0.595, 0.6387, 0.68, 0.7188, 0.755, 0.7888, 0.82, 0.8488, 0.875, 0.8988, 0.92, 0.9388, 0.955, 0.9688, 0.98, 0.9888, 0.995, 0.9988, 1)', fill: 'both' });
vawe
import { easeInOutQuad } from '../../core/motion/curves.js';
import { curveToLinear } from '../../core/motion/springs.js';

const easing = curveToLinear(easeInOutQuad, { tolerance: 0.002 }); // the linear() string above
const x = easeInOutQuad(u);                                         // per-frame code, u in 0..1

When to use it, and when to avoid it

Use it for

  • Moves between two resting positions: camera pushes, slides and loops.
  • For quad: small UI changes and hover states where a light ease is enough.

Avoid it for

  • Quick UI feedback under 200 ms: the slow start delays the response.
  • For quad: hero moves: the stop is too soft to feel designed.

The nearest vawe ease

The closest of the nine vawe After Effects eases is glide, an RMS gap of 0.0295 in progress. After Effects and vawe set the shape with two handles, so it can be tuned where a named curve cannot.