Inches to millimeters (in to mm)
The answer, the exact formula and a table with the values people look up most.
1 in = 25.4 mm1 mm = 0.0393701 inMillimeters = Inches × 25.4Example: 1.5 in = 38.1 mm
1 in = 25.4 mm
Conversions people ask for most
Convert inches to millimeters
| in | mm |
|---|---|
| 0.125 in | 3.175 mm |
| 0.25 in | 6.35 mm |
| 0.375 in | 9.525 mm |
| 0.5 in | 12.7 mm |
| 0.625 in | 15.875 mm |
| 0.75 in | 19.05 mm |
| 1 in | 25.4 mm |
| 1.5 in | 38.1 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 4 in | 101.6 mm |
| 5 in | 127 mm |
| 6 in | 152.4 mm |
| 10 in | 254 mm |
| 12 in | 304.8 mm |
The factor is exact: it comes from the official definition of the units. The table rounds to a few decimals; the converter above gives up to 10 significant digits.
The two units
Inch in
An inch is exactly 2.54 centimeters by international agreement since 1959; it is used mainly in the United States and for screens and tires everywhere.
Millimeter mm
A millimeter is one thousandth of a meter; it is the usual unit in technical drawings and engineering.
Frequently asked questions
How many millimeters are 1.5 inches?
1.5 in = 38.1 mm.
What is the formula to convert inches to millimeters?
Millimeters = Inches × 25.4. 1.5 in = 38.1 mm.
Is this conversion exact?
Yes. The factor comes from the international definition of both units, so the only difference you may see is rounding.