1 inch to millimeters
1 in = 25.4 mm. Change the amount below, or read the formula and the reference table further down.
1 inch equals
millimeters
1 in = 25.4 mm
The formula
Inches and millimeters both measure length from the same zero, so a single multiplier does the job.
mm = in × 25.4
Going the other way? Convert millimeters to inches.
Inches to millimeters table
Values either side of 1 in.
| Inches (in) | Millimeters (mm) |
|---|---|
| -4 | -101.6 |
| -3.5 | -88.9 |
| -3 | -76.2 |
| -2.5 | -63.5 |
| -2 | -50.8 |
| -1.5 | -38.1 |
| -1 | -25.4 |
| -0.5 | -12.7 |
| 0 | 0 |
| 0.5 | 12.7 |
| 1 | 25.4 |
| 1.5 | 38.1 |
| 2 | 50.8 |
| 2.5 | 63.5 |
| 3 | 76.2 |
| 3.5 | 88.9 |
| 4 | 101.6 |
| 4.5 | 114.3 |
| 5 | 127 |
| 5.5 | 139.7 |
| 6 | 152.4 |
Questions people ask
- How many millimeters are in a inch?
- One inch equals 25.4 millimeters.
- How do I convert inches to millimeters by hand?
- Multiply the number of inches by 25.4. For a rough check, 25.4 is close enough for most everyday use.
- What is 1 inch in millimeters?
- 1 inch is 25.4 millimeters.
Calcuit generates this page from a unit table, so the factors here match every other page on the site.