Inches to Millimetres Converter
Convert inch to millimetre instantly. Type a value below — the result updates as you type.
When you need to convert inch to millimetre
Length conversions come up constantly in DIY, travel and online shopping — sizing furniture, reading a height in a different system, or checking a screen or fabric measurement listed in unfamiliar units.
Millimetres-to-inches conversions turn up in woodworking, 3D printing, fasteners and rainfall figures where fine precision matters.
Typical values: 0.5 in is about 12.7 mm, and 100 in works out to roughly 2540 mm. Because the ratio is fixed at 25.4, you can scale any amount linearly — doubling the inches doubles the millimetres.
Metric and imperial length units coexist worldwide, so the same object is often quoted two ways depending on the country.
How to convert inch to millimetre
One inch equals 25.4 millimetres. To convert, multiply the number of inches by 25.4:
millimetres = inches × 25.4
For example, 10 inches × 25.4 = 254 millimetres.
Inches to millimetres conversion table
| Length (in) | Millimetres (mm) |
|---|---|
| 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 |
| 50 in | 1270 mm |
| 100 in | 2540 mm |
FAQ
How many millimetres are in a inch?
One inch = 25.4 millimetres.
How do I convert millimetres back to inches?
Divide by 25.4, or use the millimetres to inches converter.