Inches to Millimeters
1 inch = 25.4 millimeters (mm)
Convert inches to millimeters instantly. 1 inch = 25.4 millimeters. Free, accurate, with conversion table and formula.
Inch (in)
Millimeter (mm)
| Unit | 1 in equals |
|---|---|
| Nanometer (nm) | 2.54000e+7 |
| Micrometer (µm) | 25,400 |
| Millimeter (mm) | 25.4 |
| Centimeter (cm) | 2.54 |
| Meter (m) | 0.0254 |
| Kilometer (km) | 0.0000254 |
| Inch (in) | 1 |
| Foot (ft) | 0.0833333 |
| Yard (yd) | 0.0277778 |
| Mile (mi) | 0.0000157828 |
| Nautical Mile (nmi) | 0.0000137149 |
How to convert inches to millimeters
- 1Take your value in inches (in).
- 2Multiply by 25.4.
- 3The result is your value in millimeters (mm).
Inches to Millimeters conversion table
| Inches (in) | Millimeters (mm) |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 5 | 127 |
| 10 | 254 |
| 25 | 635 |
| 50 | 1,270 |
| 100 | 2,540 |
| 250 | 6,350 |
| 500 | 12,700 |
| 1,000 | 25,400 |
Frequently asked
How many millimeters are in a inch?
1 inch equals 25.4 millimeters (mm).
How do I convert inches to millimeters?
Multiply the number of inches by 25.4 to get millimeters.
What is 10 inches in millimeters?
10 in equals 254 mm.
What is 100 inches in millimeters?
100 in equals 2,540 mm.
How do I convert millimeters back to inches?
Multiply millimeters by 0.0393701 (the reciprocal) or use the swap button above.
Where you'll actually use this
Length measurements describe how far apart two points are along a straight line. The metric system uses the meter as its base unit, while imperial systems rely on inches, feet, yards, and miles.
- Construction & DIY
Floor plans, lumber lengths, drywall sheets, and fixture clearances all swap between metric and imperial depending on supplier and region.
- Travel & navigation
Convert driving distances from kilometers to miles when crossing borders or comparing routes on different map services.
- Sports & fitness
Running splits, swim distances, and track events bounce between meters, yards, and miles depending on the event format.
- International shopping
TV diagonals, monitor sizes, fabric, and shoe measurements are quoted in inches, cm, or mm by region.
Common mistakes to avoid
- Mixing up cm and m
100 cm equals 1 m. A common error is reading 1.5 m as 15 cm — always check the decimal place.
- Foot vs feet symbol
Single quote (′) means feet, double (″) means inches. 5′10″ is five feet ten inches, not feet-and-feet.
- Statute vs nautical miles
A nautical mile (1,852 m) is about 15% longer than a statute mile (1,609 m). Used for sea and air navigation.
Did you know?
Since 2019 the meter is defined by the speed of light — exactly 1/299,792,458 of a second of travel.
The Roman mile was 1,000 paces (mille passus). The English mile was later standardized to 8 furlongs of 660 feet each.
History & context
The metric system was adopted by France in 1795 and now serves as the legal measurement system in nearly every country. The US, Liberia, and Myanmar remain the only nations still officially using imperial units for daily measurement.
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