coderef

rch unitBaseline · Newly available

The rch CSS length unit is a font-relative length equal to the value of the ch unit on the root element. ch length is based on the width of the zero (0) character.

Works in the latest version of every major browser, but older devices may not support it yet. Baseline since Jan 13, 2026.

How to use ↓Compare browsers

Browser support

DesktopChrome
1–110Not supported
111+Supportedsince Mar 7, 2023
Current: 155
Edge
12–110Not supported
111+Supportedsince Mar 13, 2023
Current: 154
Firefox
1–146Not supported
147+Supportedsince Jan 13, 2026
Current: 157
Safari
1–17.1Not supported
17.2+Supportedsince Dec 11, 2023
Current: 27
MobileChrome Android
18–110Not supported
111+Supportedsince Mar 7, 2023
Current: 155
Firefox Android
4–146Not supported
147+Supportedsince Jan 13, 2026
Current: 157
Safari iOS
1–17.1Not supported
17.2+Supportedsince Dec 11, 2023
Current: 27

How to use

Every current browser supports this, but it only became Baseline on Jan 13, 2026. Use it as a progressive enhancement, or keep a fallback if you support older devices.

Example

Full syntax and examples are on MDN — see the links below.

Feature detection

There’s no simple runtime check for this feature; rely on the support table and test in your target browsers.

Specification