Convert Inches (in) to Millimeters (mm) instantly — free length converter, no sign-up.
1 in (inches) = 25.4 mm (millimeters)
mm = in × 25.4
To convert 25 inches to millimeters, multiply by 25.4 (25 × 25.4) — which gives 635 mm.
| Inches | Millimeters |
|---|---|
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 25 in | 635 mm |
| 50 in | 1270 mm |
| 100 in | 2540 mm |
| 500 in | 12700 mm |
| 1000 in | 25400 mm |
Length conversions move between the metric system (millimetres, centimetres, metres, kilometres), which is decimal and scales by powers of ten, and the imperial/US customary system (inches, feet, yards, miles), which does not. The metre is the SI base unit and every conversion here is defined against it: the inch has been exactly 25.4 mm since the 1959 international yard and pound agreement, which is why these factors are exact rather than approximate.