Inches to mm
1 in = 25.4 mm. Type in either box to convert both ways, in exact decimals.
The formula
1 in = 25.4 mm
To convert inches to millimetres, multiply by 25.4.
An inch is exactly 25.4 millimetres, so millimetres and inches convert exactly.
Common values
| Inches | Millimetres |
|---|---|
| ⅛ | 3.175 |
| ¼ | 6.35 |
| ⅜ | 9.525 |
| ½ | 12.7 |
| ¾ | 19.05 |
| 1 | 25.4 |
| 2 | 50.8 |
| 3 | 76.2 |
| 4 | 101.6 |
| 6 | 152.4 |
| 12 | 304.8 |
Worked out by Figure's own converter: every value is exact.
How to use it
Type a number in the top box and the answer appears in the bottom one as you type; type in the bottom box to go the other way. The round button swaps the units, the unit names open every other unit, and the Every unit list shows the same amount in all of them. Sums work in the boxes too. Nothing is uploaded and there is no account.
Good for:
- Drill bits, screws, bolts and spanners in metric and imperial sizes
- Rainfall and snowfall totals
- 3D printing, woodworking and model making
- Bike parts, tyres and camera lenses
- Jewellery, watch straps and small parts
Questions
How many millimetres is 1 inch?
1 inch is exactly 25.4 millimetres.
How many millimetres is a quarter of an inch?
A quarter of an inch is exactly 6.35 mm.
More length
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