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Inch to Millimeter Converter

VerifiedLast reviewed: Apr 22, 2026Fact checked by: Adil BaltiFactor: 1 in = 25.4 mmSource: BIPM
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What is Inch to Millimeter Converter

An inch to millimeter converter translates length measurements from inches (in) to millimeters (mm). Using the precise standard where 1 inch is equal to 25.4 millimeters, this utility ensures exact conversions for manufacturing, carpentry, and engineering tasks.

Definitions of Inch and Millimeter

What is Inch?

An inch is a unit of length in the US customary and imperial systems equal to one-twelfth of a foot. It is frequently used for screen sizes and small dimensions.

What is Millimeter?

A millimeter is a unit of length in the metric system equal to one-thousandth of a meter. It is widely used for precise engineering and fine measurements.

Inch to Millimeter Formula

mm=in×25.4\text{mm} = \text{in} \times 25.4

Conversion explanation: Multiply the value in Inch by 25.4 to get the equivalent value in Millimeter.

How to Convert Inch to Millimeter

To convert a value from inches to millimeters, multiply the value by the conversion multiplier:

Millimeters = inches × 25.4

Step-by-Step Example

Converting a 0.25-inch drill bit diameter into millimeters:

  • Identify the multiplier factor: 25.4.
  • Multiply 0.25 by the factor: 0.25 × 25.4 = 6.35.
  • Result: 0.25 inches is equal to 6.35 millimeters.

Inch to Millimeter Conversion Table

Inch [in]Millimeter [mm]
0.01 in0.254 mm
0.1 in2.54 mm
1 in25.4 mm
2 in50.8 mm
3 in76.2 mm
4 in101.6 mm
5 in127 mm
6 in152.4 mm
7 in177.8 mm
8 in203.2 mm
9 in228.6 mm
10 in254 mm
20 in508 mm
30 in762 mm
50 in1270 mm
100 in2540 mm
500 in12700 mm
1000 in25400 mm
Rate This Inch to Millimeter Converter:
5 /5 (79 votes)

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