Convert mm to inches
1 mm = 0.0393701 in · 1 in = 25.4 mm · Exact by definition
1 mm = 0.0393701 in
The same value in other units
- centimetre
- 0.1 cm
- metre
- 0.001 m
- kilometre
- 1e-6 km
- foot
- 0.00328084 ft
- yard
- 0.00109361 yd
- mile
- 6.21371e-7 mi
- nautical mile
- 5.39957e-7 nmi
Settings
Digits kept in the answer. Automatic keeps six, which hides floating-point noise without losing anything real.
Convert a whole list
Paste one conversion per line, written the way you would say it: "5 km to mi". Handy for a column copied out of a spreadsheet.
Length
mm to inches: conversion table
| millimetre | inch |
|---|---|
| 1 mm | 0.0393701 in |
| 2 mm | 0.0787402 in |
| 3 mm | 0.11811 in |
| 5 mm | 0.19685 in |
| 10 mm | 0.393701 in |
| 20 mm | 0.787402 in |
| 25 mm | 0.984252 in |
| 50 mm | 1.9685 in |
| 100 mm | 3.93701 in |
| 250 mm | 9.84252 in |
| 500 mm | 19.685 in |
| 1000 mm | 39.3701 in |
| inch | millimetre |
|---|---|
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 20 in | 508 mm |
| 25 in | 635 mm |
| 50 in | 1270 mm |
| 100 in | 2540 mm |
| 250 in | 6350 mm |
| 500 in | 12700 mm |
| 1000 in | 25400 mm |
How the conversion works
in = mm × 0.039370079
Both units are defined exactly, so the precision of the mm to inches result depends only on the number of decimal places you choose.
METHOD AND SOURCES
Where the conversion factors come from
Results are calculated from the unit definitions stored in the converter, not copied from a lookup table. For exact units, every value in the table follows from the same factor shown in the formula above.
- BIPM — SI Brochure
The official definitions of the International System of Units (SI).
- NIST SP 811 — Conversion factors
Conversion-factor tables for SI and non-SI units.
Keep going