Inches to Millimeters Converter – in to mm
Need to convert inches to millimeters? This fast and accurate in to mm converter is ideal for engineering, manufacturing, DIY, jewelry, and 3D printing. Enter a value in inches to get the result in millimeters immediately.
Conversion Formula
Formula to convert inches to Millimeters:
Millimeters = Inches × 25.4
Example:
Convert 2.5 inches to millimeters:
2.5 × 25.4 = 63.5 mm
Quick Reference Table
| Inches (in) | Millimeters (mm) |
|---|---|
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 4 in | 101.6 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 12 in (1 ft) | 304.8 mm |
About This Converter
1 inch = 25.4 millimeters exactly (international agreement).
Ideal for converting imperial specs to metric drawings.
Accepts whole numbers or decimals (e.g., 3, 3.55 in).
Configure rounding to suit your use case (2–3 decimals typical).
FAQs
How many millimeters are in an inch?
Exactly 25.4 mm.
What is 6 inches in mm?
6 x 2.54 = 152.4 mm
How do I quickly convert inches to mm?
Multiply by 25.4 (or use this calculator!).