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EasingClassic eases

easeInQuart

It starts slowly and ends fast. A strong ease: most of the travel happens in the fast section.

easeInQuart reaches 50% of its travel at 84% of the time and 90% at 97%. Its peak speed is 4x the average.

Classic easesfamily: quartpeak 4x

Progress against time0100.51progress50%90%
The dashed line is linear. The dots mark 50% and 90% of the travel.
Velocity, in multiples of average speed01400.51speed, 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.

easeInQuart
linear

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

Numbers

50% of travel
84%of the time
90% of travel
97%of the time
After 10% of time
0.01%of the travel is done
Peak speed
4xtimes the average
Overshoot
0%stays inside the end
Undershoot
0%never below the start
linear() points
41at a 0.002 tolerance
cubic-bezier
exactworst gap 0.4 points

Copy the code

css linear() (exact)
animation-timing-function: linear(0, 0, 0, 0, 0.0001, 0.0002, 0.0005, 0.0009, 0.0016, 0.0026, 0.0039, 0.0057, 0.0081, 0.0112, 0.015, 0.0198, 0.0256, 0.0326, 0.041, 0.0509, 0.0625, 0.076, 0.0915, 0.1093, 0.1296, 0.1526, 0.1785, 0.2076, 0.2401, 0.2763, 0.3164, 0.3608, 0.4096, 0.4633, 0.522, 0.5862, 0.6561, 0.7321, 0.8145, 0.9037, 1);
cubic-bezier (matches within 0.5%)
animation-timing-function: cubic-bezier(0.51, 0, 0.74, 0);

Least-squares fit to the easeInQuart curve; the worst gap is 0.4 points of travel. The linear() string is exact.

web animations api
el.animate({ translate: ['0 0', '240px 0'] }, { duration: 600, easing: 'cubic-bezier(0.51, 0, 0.74, 0)', fill: 'both' });
vawe
import { easeInQuart } from '../../core/motion/curves.js';
import { curveToLinear } from '../../core/motion/springs.js';

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

When to use it, and when to avoid it

Use it for

  • Exits and build-ups that leave the frame at speed.
  • For quart: panels and overlays that need a clear stop.

Avoid it for

  • Entrances: the first frames barely move, so the viewer waits.
  • For quart: short moves under 150 ms: the slow part is too short to see.

The nearest vawe ease

The closest of the nine vawe After Effects eases is launch, an RMS gap of 0.1037 in progress. After Effects and vawe set the shape with two handles, so it can be tuned where a named curve cannot.