MM to Inches converter
1 mm = 0.0393700787402 in
One inch is exactly 25.4 mm. Drill bits, wrench sizes, jewellery and rainfall totals are where millimetres and inches collide most often.
25.4 mm = 1 in
Formula: in = mm ÷ 25.4
25.4 mm in every length unit
- centimetre
- metre
- kilometre
- inch
- foot
- yard
- mile
- nautical mile
How to convert millimetres to inches
in = mm ÷ 25.4
Example: 25.4 mm × 0.0393700787402 = 1 in.
millimetre: 1 mm = 0.001 m (BIPM SI Brochure)
inch: 1 in = 2.54 cm exactly (NIST SP 811, App. B (1959 yard & pound agreement))
Where the number 0.039370079 comes from
Nothing is measured here. Every step below is a definition written into law or into the SI.
1 mm
MM to Inches table
| millimetres (mm) | inches (in) | Also written |
|---|---|---|
| 1 | 0.03937008 | |
| 2 | 0.07874016 | |
| 3 | 0.1181102 | |
| 4 | 0.1574803 | |
| 5 | 0.1968504 | |
| 6 | 0.2362205 | |
| 8 | 0.3149606 | |
| 10 | 0.3937008 | |
| 12 | 0.4724409 | |
| 15 | 0.5905512 | |
| 16 | 0.6299213 | |
| 19 | 0.7480315 | |
| 20 | 0.7874016 | |
| 22 | 0.8661417 | |
| 25 | 0.984252 | |
| 25.4 | 1 | |
| 30 | 1.181102 | |
| 32 | 1.259843 | |
| 35 | 1.377953 | |
| 40 | 1.574803 | |
| 50 | 1.968504 | |
| 60 | 2.362205 | |
| 75 | 2.952756 | |
| 100 | 3.937008 | |
| 150 | 5.905512 | |
| 200 | 7.874016 | |
| 300 | 11.81102 |
Questions
How many inches are in 1 millimetre?
1 mm = 0.0393700787402 in.
What is the formula to convert millimetres to inches?
in = mm ÷ 25.4. 1 mm = 0.001 m; 1 in = 2.54 cm exactly.
Is this conversion exact?
Yes. Both units are defined exactly (BIPM SI Brochure; NIST SP 811, App. B (1959 yard & pound agreement)), so the factor is exact and results are only rounded for display.
What is 25.4 mm in in?
25.4 mm = 1 in.