Convert millimetre to inch
1 millimetre = 0.03937008 inches. Enter any value below for an exact conversion.
1 mm =
0.03937008 in
inches
Need the reverse? Convert inch to millimetre →
Formula
1 millimetre = 0.03937008 inches inch = millimetres × 0.03937008 millimetre = inches × 25.4
millimetre to inch conversion table
About converting millimetres to inches
Millimetres to inches is a precision conversion for engineering, woodworking, jewellery, and hardware, where small metric dimensions must be read in inches. There are exactly 25.4 millimetres in an inch.
Method & sources
Conversions use exact legal definitions rather than rounded approximations: 1 inch = 2.54 cm and 1 pound = 0.45359237 kg (fixed by the 1959 international yard and pound agreement), 1 mile = 1.609344 km, and 1 US liquid gallon = 3.785411784 litres. Temperatures convert with °F = °C × 9⁄5 + 32 and K = °C + 273.15. Results are rounded only for display.
- NIST Special Publication 811 — Guide for the Use of the SI
- NIST Handbook 44, Appendix C — General Tables of Units of Measurement
Page last updated: October 1, 2026
Frequently asked questions
How many inches are in a millimetre?
One millimetre equals 0.03937008 inches. So 10 millimetres is 0.3937008 inches. Use the converter above for any value.
What is the formula to convert millimetres to inches?
1 millimetre = 0.03937008 inches inch = millimetres × 0.03937008 millimetre = inches × 25.4
Is the millimetre-to-inch conversion exact?
Yes. The conversion factor between millimetres and inches is defined exactly, so results are precise — only rounded for display.
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