Inch [in] to Millimeter [mm] Converter

Quick Reference

1 Inch (in) = 25.39999919 Millimeter (mm)

1 Millimeter (mm) = 0.03937008 Inch (in)

How to Convert Inch to Millimeter

1 in = 25.399999187200024 mm
1 mm = 0.03937008 in

To convert Inch to Millimeter, multiply the value by 25.39999919. To convert Millimeter back to Inch, divide by 25.39999919.

Example: convert 10 in to mm:
10 in = 10 x 25.399999187200024 = 253.99999187200024 mm

↔ Convert Millimeter to Inch

Inch

Definition: An inch (in) is a unit of length in the imperial and United States customary systems. It is defined as exactly 25.4 millimeters.

History/origin: The inch has a long and varied history, with its origins tracing back to ancient Rome. It has been defined in various ways over time, but the modern definition is based on the metric system.

Current use: Inches are commonly used in the United States, Canada, and the United Kingdom for measuring lengths, heights, and distances. They are used in construction, manufacturing, and everyday measurements.

Millimeter

Definition: A millimeter (mm) is a unit of length in the metric system, equal to one thousandth of a meter. It is a decimal fraction of the meter, the SI base unit of length.

History/origin: The millimeter is derived from the meter, which was defined in the late 18th century during the French Revolution as one ten-millionth of the distance from the equator to the North Pole along a meridian. The prefix 'milli-' denotes one thousandth.

Current use: Millimeters are widely used in engineering, manufacturing, construction, and science for precise measurements. They are commonly used in technical drawings, specifications, and for measuring small objects or distances.

Inch to Millimeter Conversion Table

Inch [in]	Millimeter [mm]
1 in	25.399999187200024 mm
2 in	50.79999837440005 mm
5 in	126.99999593600012 mm
10 in	253.99999187200024 mm
20 in	507.9999837440005 mm
50 in	1269.999959360001 mm
100 in	2539.999918720002 mm
200 in	5079.999837440004 mm
500 in	12699.999593600012 mm
1000 in	25399.999187200025 mm

Common pairs of Length

Millimeter

Millimeter to Centimeter Millimeter to Meter Millimeter to Kilometer Millimeter to Inch Millimeter to Yard

Centimeter

Centimeter to Millimeter Centimeter to Meter Centimeter to Kilometer Centimeter to Inch Centimeter to Yard

Meter

Meter to Millimeter Meter to Centimeter Meter to Kilometer Meter to Inch Meter to Yard

Kilometer

Kilometer to Millimeter Kilometer to Centimeter Kilometer to Meter Kilometer to Inch Kilometer to Yard

Inch

Inch to Millimeter Inch to Centimeter Inch to Meter Inch to Kilometer Inch to Yard

Yard

Yard to Millimeter Yard to Centimeter Yard to Meter Yard to Kilometer Yard to Inch

US Survey Foot

US Survey Foot to Millimeter US Survey Foot to Centimeter US Survey Foot to Meter US Survey Foot to Kilometer US Survey Foot to Inch

Foot

Foot to Millimeter Foot to Centimeter Foot to Meter Foot to Kilometer Foot to Inch

Mile

Mile to Millimeter Mile to Centimeter Mile to Meter Mile to Kilometer Mile to Inch

Inch [in] to Millimeter [mm] Converter

To convert Inch to Millimeter, enter your value in the in field above and the result in mm will appear instantly. You can also use the conversion factor shown in the table on this page to calculate manually. The formula is always the same: multiply your in value by the fixed conversion ratio to get the equivalent in mm.

Our Inch to Millimeter converter uses standardized conversion factors defined by international scientific and metrological organizations. All calculations are performed with full floating-point precision. You can also choose how many decimal places to display in the result, so you get exactly the level of detail you need.

Yes, absolutely. Simply swap the source and destination units in the converter — select mm as your input unit and in as your output unit. The same precision and standardized conversion factor applies in both directions.

Converting between Inch and Millimeter comes up regularly in engineering, scientific research, construction, and everyday tasks that involve measurements from different unit systems. Our converter eliminates the risk of manual calculation errors and saves time whenever you need to switch between these two units.

Yes, the Inch to Millimeter converter is completely free. No account or registration is required, and there are no usage limits. It works on any device — smartphones, tablets, and desktop computers — directly in your browser.

Inch and Millimeter are both units used to measure the same physical quantity, but they belong to different measurement systems or represent different scales. The mathematical relationship between them is fixed and constant, which is what makes accurate conversion possible. Scroll up to see the exact conversion factor, formula, and a reference table for common values.

Inch [in] to Millimeter [mm] Converter

Quick Reference

1 Inch (in) = 25.39999919 Millimeter (mm)

1 Millimeter (mm) = 0.03937008 Inch (in)

How to Convert Inch to Millimeter

1 in = 25.399999187200024 mm
1 mm = 0.03937008 in

To convert Inch to Millimeter, multiply the value by 25.39999919. To convert Millimeter back to Inch, divide by 25.39999919.

Example: convert 10 in to mm:
10 in = 10 x 25.399999187200024 = 253.99999187200024 mm

↔ Convert Millimeter to Inch

Inch

Definition: An inch (in) is a unit of length in the imperial and United States customary systems. It is defined as exactly 25.4 millimeters.

Millimeter

Definition: A millimeter (mm) is a unit of length in the metric system, equal to one thousandth of a meter. It is a decimal fraction of the meter, the SI base unit of length.

Inch to Millimeter Conversion Table

Inch [in]	Millimeter [mm]
1 in	25.399999187200024 mm
2 in	50.79999837440005 mm
5 in	126.99999593600012 mm
10 in	253.99999187200024 mm
20 in	507.9999837440005 mm
50 in	1269.999959360001 mm
100 in	2539.999918720002 mm
200 in	5079.999837440004 mm
500 in	12699.999593600012 mm
1000 in	25399.999187200025 mm