Inches to mm – convert inches to millimetres
Convert inches to millimetres (in to mm) for carpentry, metalwork, 3D printing, electronics and more. This page opens the main length converter with inches → millimetres pre-selected.
Open the interactive inches → mm converter:
Use main converter (in → mm) or switch to mm → inchesOn the homepage you can also switch between inches, mm, cm, metres, feet and yards using the dropdowns and swap button.
Quick reference: inches to mm
The exact factor is 1 in = 25.4 mm. Some handy rounded values:
| Inches (in) | Millimetres (mm) |
|---|---|
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 4 in | 101.6 mm |
| 6 in | 152.4 mm |
| 10 in | 254 mm |
| 12 in (1 ft) | 304.8 mm |
| 36 in (1 yd) | 914.4 mm |
Why convert inches to millimetres?
Common reasons to convert inches to mm include:
- Following US-based DIY or woodworking plans using metric tools.
- Checking monitor, phone and laptop sizes against metric dimensions.
- Preparing CAD or 3D printing models that must be in millimetres.
- Matching imperial product specs with metric technical drawings.
More length converters on this site
On the main converter all length units convert via metres, so inches, millimetres and other units stay consistent.
Page last updated: 2 December 2025.