MM to Inches Converter

Type a number of millimeters and this converter shows the answer in inches instantly (1 mm = 0.0393701 in). Below the converter you will find a ready-made mm to in table, and further down the formula with a worked example.

Millimeters are used for drill bits, screws, bolts, wrenches, jewelry, camera lenses, rainfall and 3D printing, while many tools and hardware in the US are sized in inches and fractions of an inch. Converting tells you that a 10 mm socket is just over 3/8 in (0.394 in versus 0.375 in), a 6 mm drill is close to 15/64 in, and 25 mm of rain is about one inch.

How to use the MM to Inches tool

1. Enter the value in millimeters in the Value box. Decimals such as 5.5 are fine.
2. The result in inches appears straight away, rounded to six significant digits.
3. Check the formula line under the result to see exactly how it was calculated.
4. Press ⇄ to convert inches back to millimeters, or pick any other unit from the lists.
5. Use Copy result, or look up common values in the conversion table.

Why use ToolOrca MM to Inches

• Exact factor: 1 mm = 0.0393701 in
• Conversion table: mm to in
• Formula and worked example included
• Instant result as you type
• Converts to every other length unit too
• Free, private and works offline

How to convert millimeters to inches

A millimeter is one thousandth of a meter. Since the international yard and pound agreement of 1959, one inch is defined as exactly 2.54 centimeters. So 1 mm = 0.0393700787 in, and 1 in = 25.4 mm exactly.

To convert millimeters to inches, divide the number of millimeters by 25.4. Multiplying by 0.0393701 gives the same answer to six significant digits.

Worked example: 10 mm ÷ 25.4 = 0.393701 in.

Quick mental math for mm to in

Divide by 25: 50 mm ÷ 25 = 2 in (exact 1.969 in). Useful fractions: 3.175 mm = 1/8 in, 6.35 mm = 1/4 in, 12.7 mm = 1/2 in, 19.05 mm = 3/4 in.

Need the opposite direction? Use the inches to millimeters converter, or switch units with the ⇄ button above.