Inch to Millimeter Converter
1 inch is exactly 25.4 millimeters. Convert inches (in) to millimeters (mm) below: type a value and the result updates as you type.
in to mm calculator
Result
Inch to Millimeter conversion
1 in = 25.4 mmone inch in millimeters
1 mm ≈ 0.03937007874 inone millimeter in inches
Inch (in): Exactly 0.0254 meters (international inch).
Millimeter (mm): One thousandth of a meter.
Source:Inch: International yard and pound agreement (1959); Millimeter: SI Brochure, 9th edition (BIPM, 2019)
How to convert inches to millimeters
To convert inches to millimeters, multiply the number of inches by 25.4.
Formula
mm = in × 25.4
Examples
- 5 in = 5 × 25.4 = 127 mm
- 25 in = 25 × 25.4 = 635 mm
- 100 in = 100 × 25.4 = 2540 mm
Inch to Millimeter conversion table
| Inch (in) | Millimeter (mm) |
|---|---|
| 0.1 in | 2.54 mm |
| 0.5 in | 12.7 mm |
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 20 in | 508 mm |
| 25 in | 635 mm |
| 50 in | 1270 mm |
| 100 in | 2540 mm |
| 250 in | 6350 mm |
| 500 in | 12700 mm |
| 1000 in | 25400 mm |
Values rounded to 10 significant digits where needed.
Common conversions
Frequently asked questions
- How many millimeters are in one inch?
- One inch is exactly 25.4 millimeters.
- How do I convert millimeters to inches?
- To convert millimeters to inches, divide the number of millimeters by 25.4. The formula is in = mm ÷ 25.4.
- Is this conversion exact?
- Yes. Both units have exact definitions and the factor 25.4 is exact. Displayed results are only rounded when they have many decimal places.
- Which is larger, a inch or a millimeter?
- A inch is 25.4 times larger than a millimeter. In other words, a millimeter is about 0.03937007874 of a inch.