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Millimeters-Inches Converter

- By Dr. Minas E. Lemonis, PhD - Updated: March 1, 2024

Enter the length in either of the next two fields and get it converted instantly from mm to inches or the opposite, from inches to mm. Inches are printed both in decimal and fraction form.

Millimeters [mm]:
Inches [in]:
icon

Inches can be decimal or fractional. For example: 5.5 or 5 1/2

Fraction [in]:
Decimal [in]:
icon

mm-to-inches conversion scale

Conversion Formulas

1 inch = 25.4 cm

1 mm ≈ 0.03937

Rule of thumb:

100 mm ≈ 4 inches

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See also
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Feet-inches converter
Length converter
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Definitions

Table of contents

Unit of millimeter

The millimeter or millimetre [mm] is a unit of length from the SI system of units. It is defined as one thousandth (1/1000) of the meter. The meter [m], is the base unit of length in SI system, and is currently established as the distance traveled by light in vacuum in \frac{1}{299\,792\,458} seconds.

Common multiple and fraction units of the metre are defined through the decimal SI prefixes, as presented in the following table:

UnitSymbol[m]
Nanometernm10-9
Micrometerμm10-6
Millimetermm0.001
Centimetercm0.01
Hectometerhm100
Kilometerkm1000
MegameterMm106

Unit of inch

Inch [in] is a unit of length in the Imperial and US customary system of units. It was historically conceived as the length of 3 barley-corns. Today, it is defined through the meter SI unit as: 1 in = 0.0254 m (= 2.54 cm = 25.4 mm).

Multiple units of the inch are defined as shown in the table:

UnitSymbol[in]
Footft12
Yardyd36
Milemi63360

How to convert inches to mm

  • Multiply distance in [in] with 25.4
  • The result is the distance in mm

For example, to convert 1/2 inches to mm, do: 0.5\times 25.4 = 12.7 mm

How to convert mm to inches

  • Divide distance in [mm] by 25.4
  • The result is the distance in inches

For example, to convert 150 mm to inches, do: 150/25.4 \approx 5.91 inches

Conversion table from mm to inches

In the following table some typical distances in millimeters are converted to inches:

[mm][in]
0.50.01969
10.03937
20.07874
30.1181
50.1969
100.3937
120.4724
200.7874
301.181
401.575
501.969
1003.937
2007.874
30011.81
40015.75
50019.69
60023.62
70027.56
80031.5
90035.43
100039.37

Conversion table from inches to mm

In the following table some typical distances in inches are converted to millimeters:

[in][mm]
0.1253.175
0.256.35
0.3759.525
0.512.7
125.4
250.8
376.2
5127
10254
12304.8
20508
30762
501270
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See also
Inches-cm converter
Feet-inches converter
Length converter
Area converter
Volume converter
All quick Converters
All Unit Converters