EngiRef / Length conversion
Convert Inches to Millimeters (in to mm)
1 in = 25.4 mm. Convert inches to millimeters with the exact factor, a common-values table and a free converter.
Conversion factor
mm = in × 25.4
1 in = 25.4 mm
Multiply by 25.4 mm to go from inches to millimeters, or divide by it to come back. The factor and every value below are computed by the same converter that runs at /convert, so this page and the tool cannot disagree.
in to mm table
| Inches (in) | Millimeters (mm) |
|---|---|
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 20 in | 508 mm |
| 50 in | 1270 mm |
| 100 in | 2540 mm |
Every figure is computed at build time by the site’s own converter from the length unit registry. For a value that is not listed, put it into the interactive converter.
Frequently asked questions
How many millimeters are in one inch?
One inch is 25.4 mm, so 100 in is 2540 mm.
What is the formula to convert inches to millimeters?
mm = in × 25.4. Multiply the value in inches by 25.4 to get millimeters.
How do I convert millimeters back to inches?
in = mm × 0.0393700787, so 1 mm is 0.0393700787 in. The mm to in page carries the same table in that direction.