Quick answer: 1 in = 25.4 mm
About the Inches to Millimetres
There are 25.4 millimetres in one inche, so to convert inches to millimetres multiply by 25.4.
The table below lists common values; type any number above for an exact result.
How to convert inches to millimetres (in to mm)
- Enter your numbers (or keep the example).
- The result updates instantly as you type.
- Copy the result, or copy the link: it keeps your numbers so you can share them.
inches to millimetres conversion table
| in | 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 |
| 75 in | 1,905 mm |
| 100 in | 2,540 mm |
| 250 in | 6,350 mm |
| 500 in | 12,700 mm |
| 1,000 in | 25,400 mm |
How it's calculated
mm = in × 25.4
Features
- Instant resultsUpdates as you type.
- Shareable linkThe URL keeps your inputs.
- Reference tableCommon values on this page.
- Works offlineRuns in your browser.
Frequently asked questions
How many millimetres are in 1 inche?
1 in = 25.4 mm.
How many inches are in 1 millimetre?
1 mm = 0.03937008 in.
Is the Inches to Millimetres free?
Yes, the Inches to Millimetres is free with no sign-up, no limits and no ads covering the result.
Does it work on my phone?
Yes. It works in any modern browser on phones, tablets and computers, and keeps working offline once the page has loaded.
Last updated · Processing happens locally in your browser.