Inches to MM Converter
1 inch = 25.4 millimeters exactly.
Use this free browser reference to convert inches to millimeters. The math is deterministic and does not require a server request.
Formula
in × 25.4 = mm
Enter the source number, apply the formula, then round only at the end. Keep more decimals for engineering or craft measurements; use one or two decimals for quick everyday checks.
Quick reference table
| Input | Converted value |
|---|---|
| 1 inches | 25.4 millimeters |
| 2 inches | 50.8 millimeters |
| 6 inches | 152.4 millimeters |
| 12 inches | 304.8 millimeters |
| 24 inches | 609.6 millimeters |
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FAQ
What is the formula?
in × 25.4 = mm
How should I round the answer?
For display, round to one or two decimals. For measurement work, keep the full calculation until your final step.