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conversion
Length converter
Convert between common length units instantly.
Length converterconversion
rem to mm converter
Convert rem to millimeters instantly.
rem to mm converter
42.33333 mm
How to convert rem to mm
mm = rem × root font size in px × 25.4 ÷ 96. At the default 16 px font size, 10 rem ≈ 42.33333 mm.
CSS reference units use 96 px = 1 in, 72 pt = 1 in, and 6 pc = 1 in. Physical screen measurements can vary. This calculator rounds conversion factors to six decimal places.
An em uses the element font size; a rem uses the root element font size. The 16 px values are editable defaults, so change the font-size input to match your design.