This scaling transformation is characterized by a two-dimensional vector. Its coordinates define how much scaling is done in each direction. If both coordinates are equal, the scaling is uniform (isotropic) and the aspect ratio of the element is preserved (this is a homothetic transformation).

When a coordinate value is outside the [-1, 1] range, the element grows along that dimension; when inside, it shrinks. A negative value results in a point reflection in that dimension. The value 1 has no effect.

The scale() function is specified with either one or two values, which represent the amount of scaling to be applied in each direction.

scale(sx)

scale(sx, sy)

sx

A <number> or <percentage> representing the abscissa of the scaling vector.

sy

A <number> or <percentage> representing the ordinate of the scaling vector. If not defined, its default value is sx, resulting in a uniform scaling that preserves the element's aspect ratio.

Scaling/zooming animations are problematic for accessibility, as they are a common trigger for certain types of migraine. If you need to include such animations on your website, you should provide a control to allow users to turn off animations, preferably site-wide.

Also, consider making use of the prefers-reduced-motion media feature — use it to write a media query that will turn off animations if the user has reduced animation specified in their system preferences.

Find out more:

• MDN Understanding WCAG, Guideline 2.3 explanations
• Understanding Success Criterion 2.3.3 | W3C Understanding WCAG 2.1

HTML

<div>Normal</div>
<div class="scaled">Scaled</div>

CSS

div {
  width: 80px;
  height: 80px;
  background-color: skyblue;
}

.scaled {
  transform: scale(0.7); /* Equal to scaleX(0.7) scaleY(0.7) */
  background-color: pink;
}

Result

HTML

<div>Normal</div>
<div class="scaled">Scaled</div>

CSS

div {
  width: 80px;
  height: 80px;
  background-color: skyblue;
}

.scaled {
  transform: scale(2, 0.5); /* Equal to scaleX(2) scaleY(0.5) */
  transform-origin: left;
  background-color: pink;
}

Result

• transform
• scale
• <transform-function>
• scale3d()
• Other individual transform properties translate and rotate