Inch to Millimeter Converter
Convert inches to millimeters with this free length converter. The exact relationship used on this page is 1 inch = 25.4 millimeters. Type any number — the result updates instantly, works on phones and desktops, and is ready to copy into homework, a spec sheet, or a shopping list.
Formula: Millimeter = Inch × 25.4
How to convert inches to millimeters
- Enter the value in inches in the converter.
- Read the equivalent amount in millimeters.
- Use the swap link if you need millimeter to inch instead.
- Check the table for common values without typing.
Worked examples
- 1 in = 25.4 mm
- 5 in = 127 mm
- 10 in = 254 mm
- 25 in = 635 mm
Conversion table
Common inches values converted to millimeters.
| in | mm |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 3 | 76.2 |
| 4 | 101.6 |
| 5 | 127 |
| 6 | 152.4 |
| 7 | 177.8 |
| 8 | 203.2 |
| 9 | 228.6 |
| 10 | 254 |
| 20 | 508 |
| 50 | 1,270 |
| 100 | 2,540 |
| 250 | 6,350 |
| 500 | 12,700 |
| 1,000 | 25,400 |
About this conversion
Inch (in) and Millimeter (mm) are both length units. Length conversion is one of the most searched measurement tasks online. Bookmark this URL when you convert inches to millimeters often, then explore related pairs in the same category if you need a different target unit.
Need the other direction? Open the millimeter to inch converter.
FAQ
How many millimeters are in 1 inch?+
1 inch equals 25.4 millimeters.
What is the formula to convert inches to millimeters?+
Millimeter = Inch × 25.4
How do I convert inches to millimeters by hand?+
Multiply the inch value by 25.4. Example: 10 inches × 25.4 = 254 millimeters.
Is this in to mm converter accurate?+
Yes. Linear conversions use internationally agreed factors relative to SI. Temperature and inverse fuel units use the standard offset or reciprocal formulas, not a guessed scale factor.