font-size-adjust

Baseline 2024

Newly available

Since ⁨July 2024⁩, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

The font-size-adjust attribute allows authors to specify an aspect value for an element that will preserve the x-height of the first choice font in a substitute font.

Note: As a presentation attribute, font-size-adjust also has a CSS property counterpart: font-size-adjust. When both are specified, the CSS property takes priority.

You can use this attribute with the following SVG elements:

Example

html,
body,
svg {
  height: 100%;
}

html

<svg
  width="600"
  height="80"
  viewBox="0 0 500 80"
  xmlns="http://www.w3.org/2000/svg">
  <text y="20" font-family="Times, serif" font-size="10px">
    This text uses the Times font (10px), which is hard to read in small sizes.
  </text>
  <text y="40" font-family="Verdana, sans-serif" font-size="10px">
    This text uses the Verdana font (10px), which has relatively large lowercase
    letters.
  </text>
  <text
    y="60"
    font-family="Times, serif"
    font-size="10px"
    font-size-adjust="0.58">
    This is the 10px Times, but now adjusted to the same aspect ratio as the
    Verdana.
  </text>
</svg>

Usage notes

Default value	`none`
Value	`none` \| `<number>`
Animatable	Yes

none

Choose the size of the font based only on the font-size property.

<number>

Choose the size of the font so that its lowercase letters (as determined by the x-height of the font) are the specified number times the font-size.

The number specified should generally be the aspect ratio (ratio of x-height to font size) of the first choice font-family. This means that the first-choice font, when available, will appear the same size in browsers, whether or not they support font-size-adjust.

0 yields text of zero height (hidden text).