MM to Inches converter

How to convert millimeters to inches

To convert millimeters to inches, use in = mm ÷ 25.4. For example, 50 mm is 1.9685 in. Type any value in the converter above and the result updates instantly.

The MM to Inches formula

The conversion is in = mm ÷ 25.4. One millimeter equals 0.0393701 in. This conversion is exact: millimeter is defined precisely in terms of inch, so the only rounding is in the digits shown.

MM to Inches conversion table

Where millimeters and inches are used

Millimeters are used for precise measurements: engineering, machining, photography (lens and sensor sizes) and hardware.

Inches are the standard for screen sizes, tires, pipes, paper and tool sizes everywhere, and for everyday lengths in the United States.

Worked examples

These examples use the formula above, so you can check the converter or do the same by hand:

• 2 mm = 0.0787402 in
• 10 mm = 0.393701 in
• 25 mm = 0.984252 in

Converting millimeters to inches in your head

As a quick estimate, multiply by 0.039 (rounded).

Inches to MM reference table

For the opposite direction, these values are handy to have at hand:

Common mistakes to avoid

• Do not confuse the international inch (exactly 25.4 mm) with the US survey foot used in old land records; everyday conversions use the international values.
• Feet and inches are often written together: 5 ft 9 in is 69 inches, or 175.26 cm.

About this converter

The converter accepts whole numbers, decimals and negative values, gives the result as you type, and uses full precision internally, so what you copy is as accurate as it can be. It runs in your browser: nothing you type is sent to a server, it keeps working offline once the page has loaded, and there is nothing to install.

Need the opposite direction? Use the Inches to MM converter.