Unit Rulebook

Type a unit, or a word from its description.

    Support matrix

    All 63 units against the seven main browsers. Each cell gives the first version that supports the unit.

    Support data: MDN browser-compat-data 8.1.7, checked 2026-11-01.

    What the Baseline labels mean

    Safe to use
    Baseline: widely available
    Use with a fallback
    Baseline: newly available since January 2026
    Limited support
    Missing in some major browsers
    Not usable
    No property accepts it in any main browser

    Baseline: "newly" once the last of chrome, chrome_android, edge, firefox, firefox_android, safari, safari_ios ships; "widely" after 30 months.

    Filter the table

    Browser support of every CSS unit, by group. The browser columns give the first version with support.
    UnitBaselineChromeChrome AndroidEdgeFirefoxFirefox AndroidSafariSafari iOSEstimated usage
    Absolute 7 units
    px Safe to use 1+ 18+ 12+ 1+ 4+ 1+ 1+100.0%
    pt Safe to use 1+ 18+ 12+ 1+ 4+ 1+ 1+100.0%
    pc Safe to use 1+ 18+ 12+ 1+ 4+ 1+ 1+100.0%
    in Safe to use 1+ 18+ 12+ 1+ 4+ 1+ 1+100.0%
    cm Safe to use 1+ 18+ 12+ 1+ 4+ 1+ 1+100.0%
    mm Safe to use 1+ 18+ 12+ 1+ 4+ 1+ 1+100.0%
    Q Safe to use 63+ 63+ 79+ 49+ 49+ 13.1+ 13.4+99.9%
    Font-relative 12 units
    em Safe to use 1+ 18+ 12+ 1+ 4+ 1+ 1+100.0%
    rem Safe to use 4+ 18+ 12+ 3.6+ 4+ 5+ 4+100.0%
    ch Safe to use 27+ 27+ 12+ 1+ 4+ 7+ 7+100.0%
    rch Use with a fallback 111+ 111+ 111+ 147+ 147+ 17.2+ 17.2+96.6%
    ex Safe to use 1+ 18+ 12+ 1+ 4+ 1+ 1+100.0%
    rex Use with a fallback 111+ 111+ 111+ 147+ 147+ 17.2+ 17.2+96.6%
    cap Safe to use 118+ 118+ 118+ 97+ 97+ 17.2+ 17.2+96.9%
    rcap Use with a fallback 118+ 118+ 118+ 147+ 147+ 17.2+ 17.2+96.2%
    ic Safe to use 106+ 106+ 106+ 97+ 97+ 15.4+ 15.4+99.4%
    ric Use with a fallback 111+ 111+ 111+ 147+ 147+ 17.2+ 17.2+96.6%
    lh Safe to use 109+ 109+ 109+ 120+ 120+ 16.4+ 16.4+98.6%
    rlh Safe to use 111+ 111+ 111+ 120+ 120+ 16.4+ 16.4+97.8%
    Percentage 1 unit
    % Safe to use 1+ 18+ 12+ 1+ 4+ 1+ 1+100.0%
    Viewport 24 units
    vw Safe to use 20+ 25+ 12+ 19+ 19+ 6+ 6+100.0%
    vh Safe to use 20+ 25+ 12+ 19+ 19+ 6+ 6+100.0%
    vi Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    vb Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    vmin Safe to use 26+ 26+ 12+ 19+ 19+ 7+ 7+100.0%
    vmax Safe to use 26+ 26+ 16+ 19+ 19+ 7+ 7+100.0%
    svw Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    svh Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    svi Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    svb Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    svmin Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    svmax Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    lvw Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    lvh Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    lvi Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    lvb Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    lvmin Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    lvmax Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    dvw Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    dvh Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    dvi Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    dvb Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    dvmin Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    dvmax Safe to use 108+ 108+ 108+ 101+ 101+ 15.4+ 15.4+99.2%
    Container 6 units
    cqw Safe to use 105+ 105+ 105+ 110+ 110+ 16+ 16+99.2%
    cqh Safe to use 105+ 105+ 105+ 110+ 110+ 16+ 16+99.2%
    cqi Safe to use 105+ 105+ 105+ 110+ 110+ 16+ 16+99.2%
    cqb Safe to use 105+ 105+ 105+ 110+ 110+ 16+ 16+99.2%
    cqmin Safe to use 105+ 105+ 105+ 110+ 110+ 16+ 16+99.2%
    cqmax Safe to use 105+ 105+ 105+ 110+ 110+ 16+ 16+99.2%
    Flexible 1 unit
    fr Safe to use 57+ 57+ 16+ 52+ 52+ 10.1+ 10.3+100.0%
    Special 12 units
    deg Safe to use 2+ 18+ 12+ 3.6+ 4+ 4+ 3.2+100.0%
    grad Safe to use 2+ 18+ 12+ 3.6+ 4+ 4+ 3.2+100.0%
    rad Safe to use 2+ 18+ 12+ 3.6+ 4+ 4+ 3.2+100.0%
    turn Safe to use 2+ 18+ 12+ 13+ 14+ 4+ 3.2+100.0%
    s Safe to use 1+ 18+ 12+ 4+ 4+ 3.1+ 2+100.0%
    ms Safe to use 1+ 18+ 12+ 4+ 4+ 3.1+ 2+100.0%
    Hz Not usable No property accepts it in any main browsern/a (no support data)
    kHz Not usable No property accepts it in any main browsern/a (no support data)
    dpi Safe to use 29+ 29+ 12+ 8+ 8+ 16+ 16+99.5%
    dpcm Safe to use 29+ 29+ 12+ 8+ 8+ 16+ 16+99.5%
    dppx Safe to use 29+ 29+ 12+ 16+ 16+ 16+ 16+99.5%
    x Safe to use 68+ 68+ 79+ 62+ 62+ 16+ 16+99.5%

    About the usage estimate

    Estimated usage is the share of traffic from these seven browsers that runs a version with support. For each browser it adds up the usage of every version from the first supported one onward. Usage comes from caniuse-lite 1.0.30001820, checked 2026-11-02.

    It is an estimate, not a measurement. Partial support counts as support, and traffic from browsers outside the seven is left out. The seven carry 95.3% of all traffic in that data.

    n/a: a unit with no browser data has no version to count from.