1 in = 25.4 mm
One inch equals exactly 25.4 millimeters.
Conversion Formula
mm = inches x 25.4
Quick Converter
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Inches to Millimeters Reference Table
| Inches (in) | Millimeters (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 |
| 15 in | 381 mm |
| 20 in | 508 mm |
| 25 in | 635 mm |
| 50 in | 1270 mm |
| 75 in | 1905 mm |
| 100 in | 2540 mm |
| 150 in | 3810 mm |
| 200 in | 5080 mm |
| 250 in | 6350 mm |
| 500 in | 12700 mm |
| 750 in | 19050 mm |
| 1000 in | 25400 mm |
| 5000 in | 127000 mm |
How to Convert Inches to Millimeters
To convert inches to millimeters, use the formula: mm = inches x 25.4. One inch equals exactly 25.4 millimeters.
Quick Example
10 in = 254 mm
About the Inches to Millimeters Conversion
One inch is defined as exactly 25.4 millimeters, so this conversion is precise. It is essential when imperial drawings or US-made parts must be specified for metric manufacturing and CNC work.
Worked example: A 0.5-inch pipe equals 0.5 x 25.4 = 12.7 millimeters. A 4-inch screen measures 101.6 mm.
Common Uses
In practice, converting inches to millimeters comes up most often for programming CNC and 3D-printing dimensions, specifying metric drill and tap sizes, converting imperial blueprints, and matching hardware across measurement systems.
Frequently Asked Questions
How do I convert inches to millimeters? + −
Use the formula: mm = inches x 25.4. One inch equals exactly 25.4 millimeters. For example, 10 in equals 254 mm.
What is the conversion factor from inches to millimeters? + −
The conversion factor is 25.4. Multiply any value in inches by 25.4 to get the equivalent in millimeters. This factor is based on internationally agreed standards.
How many millimeters are in 10 in? + −
10 in equals 254 mm. This is calculated using the formula mm = inches x 25.4. You can verify this by checking the reference table above.
Is the inches to millimeters conversion exact? + −
Yes, this conversion is exact by international definition. One inch equals exactly 25.4 millimeters.
When would I need to convert inches to millimeters? + −
Typical situations include programming CNC and 3D-printing dimensions, specifying metric drill and tap sizes, converting imperial blueprints, and matching hardware across measurement systems.