em to mm converter

How to convert em to mm

mm = em × element font size in px × 25.4 ÷ 96. At the default 16 px font size, 10 em ≈ 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.

Typographic unit converter