vaweGitHub

EasingClassic eases

easeInSine

It starts slowly and ends fast. The gentlest family: the speed changes slowly, so it reads as breathing, not as a hit.

easeInSine reaches 50% of its travel at 67% of the time and 90% at 94%. Its peak speed is 1.57x the average.

Classic easesfamily: sinepeak 1.57x

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.

easeInSine
linear

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

Numbers

50% of travel
67%of the time
90% of travel
94%of the time
After 10% of time
1.23%of the travel is done
Peak speed
1.57xtimes 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 0.1 points

Copy the code

css linear() (exact)
animation-timing-function: linear(0, 0.0008, 0.0031, 0.0069, 0.0123, 0.0192, 0.0276, 0.0375, 0.0489, 0.0618, 0.0761, 0.0919, 0.109, 0.1275, 0.1474, 0.1685, 0.191, 0.2147, 0.2396, 0.2657, 0.2929, 0.3212, 0.3506, 0.3809, 0.4122, 0.4444, 0.4775, 0.5114, 0.546, 0.5813, 0.6173, 0.6539, 0.691, 0.7286, 0.7666, 0.8049, 0.8436, 0.8825, 0.9215, 0.9607, 1);
cubic-bezier (matches within 0.5%)
animation-timing-function: cubic-bezier(0.36, 0, 0.67, 0.48);

Least-squares fit to the easeInSine curve; the worst gap is 0.1 points of travel. The linear() string is exact.

web animations api
el.animate({ translate: ['0 0', '240px 0'] }, { duration: 600, easing: 'cubic-bezier(0.36, 0, 0.67, 0.48)', fill: 'both' });
vawe
import { easeInSine } from '../../core/motion/curves.js';
import { curveToLinear } from '../../core/motion/springs.js';

const easing = curveToLinear(easeInSine, { tolerance: 0.002 }); // the linear() string above
const x = easeInSine(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 sine: ambient loops, slow camera drift and background layers.

Avoid it for

  • Entrances: the first frames barely move, so the viewer waits.
  • For sine: moves that must hit hard: the gentle stop looks undecided.

The nearest vawe ease

The closest of the nine vawe After Effects eases is carry, an RMS gap of 0.09 in progress. After Effects and vawe set the shape with two handles, so it can be tuned where a named curve cannot.