Free Inches to MM Converter
Convert inches to millimeters with exact precision. Free, instant, works in your browser.
Formula: 1 inch = 25.4 mm
| Inches (in) | Millimeters (mm) |
|---|---|
| 1 | 25.4000 |
| 5 | 127.0000 |
| 10 | 254.0000 |
| 25 | 635.0000 |
| 50 | 1270.00 |
| 100 | 2540.00 |
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How to Convert Inches to Millimeters Online
Type the inch value and get the exact millimeter equivalent. Since 1 inch is defined as exactly 25.4 mm, this conversion is always precise — there is no rounding involved.
Why Convert Inches to Millimeters?
When working with metric tools, ordering metric hardware, or converting American pipe sizes, bolt sizes, and sheet dimensions to metric — this converter provides the exact values needed. The 25.4 mm per inch relationship is an exact definition, not an approximation.
Frequently Asked Questions
Is 1 inch exactly 25.4 mm? Yes. Since 1959, the international inch has been defined as exactly 25.4 millimeters.
What is 1/4 inch in mm? 0.25 inches equals exactly 6.35 millimeters.