Unit Rulebook

Type a unit, or a word from its description.

    CSS unit cheatsheet

    One line per unit: what it equals and whether you can rely on it. Print it, or keep it open next to your editor.

    CSS Unit Rulebook, units.bereg.dev/cheatsheet/

    Baseline marks

    Each mark is a symbol and a word, so the sheet still reads in black and white.

    Safe to use
    In every main browser for 30 months or more
    Use with a fallback
    In every main browser, for less than 30 months
    Limited support
    Missing in at least one main browser
    Not usable
    No property accepts it in any main browser

    Absolute 7 units

    Reference The CSS pixel

    • px1px = 1/96in Safe to use
    • pt1pt = 1/72in = 4/3px Safe to use
    • pc1pc = 12pt = 1/6in = 16px Safe to use
    • in1in = 96px = 2.54cm = 72pt = 6pc Safe to use
    • cm1cm = 96px / 2.54 ≈ 37.795px Safe to use
    • mm1mm = 1/10cm ≈ 3.7795px Safe to use
    • Q1Q = 1/40cm = 0.25mm ≈ 0.945px Safe to use

    Font-relative 12 units

    Reference Font size and glyph metrics

    • em1em = the font-size of the element; in font-size itself, the parent's Safe to use
    • rem1rem = font-size of :root (16px unless the reader changed the browser default) Safe to use
    • ch1ch = advance width of "0" in the element's font (0.5em if it cannot be measured) Safe to use
    • rch1rch = the value of ch on the root element Use with a fallback
    • ex1ex = x-height of the element's font (0.5em if it cannot be determined, as the specification has it) Safe to use
    • rex1rex = the value of ex on the root element Use with a fallback
    • cap1cap = cap height of the element's font (the ascent of the font if it cannot be determined, as the specification has it) Safe to use
    • rcap1rcap = the value of cap on the root element Use with a fallback
    • ic1ic = advance of 水 (U+6C34) in the element's font (1em if it cannot be measured) Safe to use
    • ric1ric = the value of ic on the root element Use with a fallback
    • lh1lh = used line-height of the element Safe to use
    • rlh1rlh = used line-height of :root Safe to use

    Percentage 1 unit

    Reference Another value

    • %N% = N/100 × the reference value of the property Safe to use

    Viewport 24 units

    Reference The viewport

    • vw1vw = 1/100 of the viewport width Safe to use
    • vh1vh = 1/100 of the viewport height (the large viewport) Safe to use
    • vi1vi = 1/100 of the viewport size in the inline direction Safe to use
    • vb1vb = 1/100 of the viewport size in the block direction Safe to use
    • vmin1vmin = 1% of min(viewport width, viewport height) Safe to use
    • vmax1vmax = 1% of max(viewport width, viewport height) Safe to use
    • svw1svw = 1/100 of the width when browser toolbars are fully shown Safe to use
    • svh1svh = 1/100 of the height when browser toolbars are expanded Safe to use
    • svi1svi = 1/100 of the small viewport in the inline direction Safe to use
    • svb1svb = 1/100 of the small viewport in the block direction Safe to use
    • svmin1svmin = 1% of min(svw, svh) Safe to use
    • svmax1svmax = 1% of max(svw, svh) Safe to use
    • lvw1lvw = 1/100 of the width when browser toolbars are retracted Safe to use
    • lvh1lvh = 1/100 of the height when browser toolbars are retracted Safe to use
    • lvi1lvi = 1/100 of the large viewport in the inline direction Safe to use
    • lvb1lvb = 1/100 of the large viewport in the block direction Safe to use
    • lvmin1lvmin = 1% of min(lvw, lvh) Safe to use
    • lvmax1lvmax = 1% of max(lvw, lvh) Safe to use
    • dvw1dvw = 1/100 of the current visible width Safe to use
    • dvh1dvh = 1/100 of the currently visible height Safe to use
    • dvi1dvi = 1/100 of the current viewport in the inline direction Safe to use
    • dvb1dvb = 1/100 of the current viewport in the block direction Safe to use
    • dvmin1dvmin = 1% of min(dvw, dvh) Safe to use
    • dvmax1dvmax = 1% of max(dvw, dvh) Safe to use

    Container 6 units

    Reference The nearest query container

    • cqw1cqw = 1/100 of the nearest container's width Safe to use
    • cqh1cqh = 1/100 of the nearest container's height Safe to use
    • cqi1cqi = 1/100 of the nearest container's inline size Safe to use
    • cqb1cqb = 1/100 of the nearest container's block size Safe to use
    • cqmin1cqmin = min(1cqi, 1cqb) Safe to use
    • cqmax1cqmax = max(1cqi, 1cqb) Safe to use

    Flexible 1 unit

    Reference Free space in a grid

    • fr1fr = one part of the space left after fixed tracks and gaps Safe to use

    Special 12 units

    Reference Its own type

    • deg360deg = 400grad = 2π rad = 1turn Safe to use
    • grad400grad = 360deg = 1turn Safe to use
    • rad2π rad = 360deg = 1turn Safe to use
    • turn1turn = 360deg = 400grad = 2π rad Safe to use
    • s1s = 1000ms Safe to use
    • ms1ms = 0.001s Safe to use
    • Hz1Hz = 1 cycle per second Not usable
    • kHz1kHz = 1000Hz Not usable
    • dpi1dpi = 1/96dppx Safe to use
    • dpcm1dpcm = 2.54dpi Safe to use
    • dppx1dppx = 96dpi = 1x Safe to use
    • x1x = 1dppx = 96dpi Safe to use

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