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 can be used as a CSS property. See the css font-size-adjust property for more information.

As a presentation attribute, it can be applied to any element but it has effect only on the following eight elements: <altGlyph>, <text>, <textPath>, <tref>, and <tspan>

<svg width="600" height="80" viewBox="0 0 500 80"
  <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 y="40" font-family="Verdana, sans-serif" font-size="10px">
    This text uses the Verdana font (10px), which has relatively large lowercase letters.
  <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.

Usage notes

Default value none
Value none | <number>
Animatable Yes
Choose the size of the font based only on the font-size property.

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).


Specification Status Comment
CSS Fonts Module Level 3
The definition of 'font-size-adjust' in that specification.
Recommendation No change
Scalable Vector Graphics (SVG) 1.1 (Second Edition)
The definition of 'font-size-adjust' in that specification.
Recommendation Initial definition

Browser compatibility

BCD tables only load in the browser

See also