Back to Length

millimeter (mm) → inch (in)

Instant conversion - enter value to see result

Use our free online converter to convert between units instantly. Enter any value in the field above to get accurate results. No signup or download required—all conversions run in your browser. Our calculator uses standard conversion factors for reliability.

0
mm=in
0.01=0.000394
0.1=0.003937
1=0.03937
2=0.07874
3=0.11811
5=0.19685
10=0.393701
20=0.787402
50=1.968504
100=3.937008
1000=39.370079

Popular conversions

More conversions in this category

Brief explanation: millimeter to inch

Length conversion multiplies by a factor. Meter is the base unit in the metric system. Kilometer = 1000 m, mile ≈ 1609 m. Foot = 0.3048 m, inch = 2.54 cm. The metric system (km, m, cm, mm) is used worldwide. The imperial system (mi, ft, in, yd) is common in the United States and United Kingdom. When converting, multiply the value by the appropriate factor—for example, to convert km to miles, multiply by 0.621371.

Related converters

Common conversion examples: millimeter to inch

Reference values for quick comparison. Use the converter above for any amount.

  • 1 millimeter=0.0394 inch
  • 5 millimeter=0.1969 inch
  • 100 millimeter=3.937 inch

About the Units

millimeter (mm)

Definition: A millimeter (mm) is a unit of length equal to one thousandth of a meter. There are 1,000 millimeters in one meter. The prefix milli- means one thousandth. It is used for precise measurements and small dimensions.
History: The millimeter became standard with the metric system. It allowed engineers and craftspeople to specify dimensions with precision without decimals. Manufacturing and machining rely heavily on millimeter tolerances.
Current use: Millimeters are used in engineering, manufacturing, and medicine. Sheet metal thickness, screw sizes, and medical measurements (e.g., tumor size) are often in millimeters. Rain gauges and rulers commonly use millimeter divisions.

inch (in)

Definition: An inch (in) is a unit of length equal to 1/12 of a foot or exactly 2.54 centimeters. It is a fundamental unit in the imperial and US customary systems for small measurements.
History: The inch has been used in England since at least the 7th century. It was historically defined by barleycorns (3 barleycorns = 1 inch). The current definition of 2.54 cm was adopted internationally in 1959.
Current use: Inches are used for screen sizes, tire dimensions, and small measurements in the US and UK. TV and monitor diagonals are often given in inches. Craft and woodworking use inches for precision.

Sources

Conversion factors and unit definitions follow international standards. For authoritative references, see: