Convert inchs to millimetres
1 in = 25.4 mm — exactly. Both units are defined against the SI, so this factor is a fraction, not an approximation.
25.4mm
As a fraction: 127/5
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1 in = 25.4 mm
Show this value in all 8 typography length units
- Metres m 0.0254
- Millimetres mm 25.4
- Inchs in 1
- CSS pixels px 96
- PostScript points pt 72
- Picas pc 6
- Quarter millimetres Q 101.6
- Twips twip 1440
Every row is Inch (in) converted through the meter, in exact rational arithmetic.
How to convert inchs to millimetres
Multiply the number of inchs by 25.4 to get millimetres.
The exact factor is 25.4 — as a fraction, 127/5.
Inch to Millimetre conversion table
| Inchs (in) | Millimetres (mm) |
|---|---|
| 1 in | 25.4 |
| 2 in | 50.8 |
| 3 in | 76.2 |
| 5 in | 127 |
| 10 in | 254 |
| 20 in | 508 |
| 25 in | 635 |
| 50 in | 1270 |
| 100 in | 2540 |
| 250 in | 6350 |
| 500 in | 12 700 |
| 1000 in | 25 400 |
Millimetre to Inch conversion table
| Millimetres (mm) | Inchs (in) |
|---|---|
| 1 mm | 0.039 370 079 |
| 2 mm | 0.078 740 157 |
| 3 mm | 0.118 110 24 |
| 5 mm | 0.196 850 39 |
| 10 mm | 0.393 700 79 |
| 20 mm | 0.787 401 57 |
| 25 mm | 0.984 251 97 |
| 50 mm | 1.968 503 9 |
| 100 mm | 3.937 007 9 |
| 250 mm | 9.842 519 7 |
| 500 mm | 19.685 039 |
| 1000 mm | 39.370 079 |
Frequently asked
How many millimetres are in a inch?
One inch equals 25.4 millimetres (in → mm). That figure is exact, not rounded.
How do you convert inchs to millimetres?
Multiply the number of inchs by 25.4 to get millimetres.
What is 1 mm in inchs?
One millimetre is 0.03937007874 inchs.
What is 10 in in mm?
10 in = 254 mm.