Convert Inch to Millimetre
Instantly convert Inch (in) to Millimetre (mm). Free and accurate.
About This Conversion
What is a Inch to Millimetre conversion?
One inch (in) is equal to 25.4 millimetre (mm). This relationship is fixed by international measurement standards and does not change. To convert any number of inch to millimetre, multiply your value by 25.4; to go the other way, divide by 25.4.
How to convert Inch to Millimetre
The conversion formula is: 1 in = 25.4 mm. Enter any value into the converter above and the result updates instantly. The formula is also shown alongside the answer so you can check the working or use it in your own calculations.
Where is this conversion used?
Length conversions are needed in construction, interior design, navigation, athletics, and everyday shopping — particularly when switching between metric and imperial products. Engineers, architects, surveyors, scientists, and runners regularly convert between units of length. Metric units (metres, kilometres) are the global standard, while miles, feet, and inches remain common in the United States and, to some degree, the United Kingdom.
Helpful tip
When measuring fabric, timber, or piping, always double-check which unit system your supplier uses before placing an order — a mix-up between feet and metres can be costly.
Formula
1 in = 25.4 mm
in to mm Conversion Table
| in | mm |
|---|---|
| 0.1 in | 2.54 mm |
| 0.5 in | 12.7 mm |
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 20 in | 508 mm |
| 25 in | 635 mm |
| 50 in | 1,270 mm |
| 100 in | 2,540 mm |
| 250 in | 6,350 mm |
| 500 in | 12,700 mm |
| 1000 in | 25,400 mm |