Work out millimetre to inch instantly with clear inputs, formula shown and shareable results.
Converting Millimetres to Inches is a single multiplication: one mm equals 0.03937008 in, so the amount is multiplied by that factor. Switching the direction divides by the same factor instead. This factor is an exact definition, not a rounded approximation, so the conversion is precise at any scale. Because 1 in = 25.4 mm exactly, a millimetre is exactly 1/25.4 of an inch.
Millimetres → Inches
in = mm × 0.03937008
Inches → Millimetres
mm = in ÷ 0.03937008
One mm is 0.03937008 in. That figure is exact by definition.
Divide by 0.03937008 instead of multiplying — or just switch the direction selector, which does it for you.