MM to Inches Converter
Convert millimetres to inches: 1 mm = 0.0393701 in. Exact factor, formula and a conversion chart.
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Result
- 1 mm
- 0.0393701 in
- 1 in
- 25.4 mm
How it's calculated
inches = millimetres × 0.0393701
To convert mm to in, divide by 25.4.
mm in every unit
| centimetre | 0.1 cm |
| metre | 0.001 m |
| kilometre | 0.000001 km |
| inch | 0.0393701 in |
| foot | 0.00328084 ft |
| yard | 0.00109361 yd |
| mile | 0.000000621371 mi |
| nautical mile | 0.000000539957 nmi |
mm to in conversion chart
| millimetre (mm) | inch (in) |
|---|---|
| 1 mm | 0.0393701 in |
| 2 mm | 0.0787402 in |
| 3 mm | 0.11811 in |
| 4 mm | 0.15748 in |
| 5 mm | 0.19685 in |
| 6 mm | 0.23622 in |
| 7 mm | 0.275591 in |
| 8 mm | 0.314961 in |
| 9 mm | 0.354331 in |
| 10 mm | 0.393701 in |
| 12 mm | 0.472441 in |
| 15 mm | 0.590551 in |
| 20 mm | 0.787402 in |
| 25 mm | 0.984252 in |
| 50 mm | 1.9685 in |
| 100 mm | 3.93701 in |
How many inches are in 1 millimetre?
1 millimetre = 0.0393701 inches. To convert millimetres to inches, divide by 25.4. For example, 10 mm = 0.393701 in and 100 mm = 3.93701 in. Enter any value above for an exact result.
The Unit Converter changes a value from one unit to another across 11 kinds of measurement: length, weight, temperature, volume, area, speed, time, digital storage, energy, pressure and fuel economy. It covers metric units (centimetres, kilograms, litres), US and UK imperial units (inches, pounds, gallons) and everyday ones such as cups, stones, acres and kilowatt-hours.
Conversions use the official definitions — 1 inch is exactly 2.54 cm, 1 pound exactly 0.45359237 kg, 1 US gallon exactly 3.785411784 litres — and the page shows the factor, the formula, the value in every other unit and a chart of common values, so you can check or reuse the numbers.
When to use it
- Converting height and weight between metric and imperial (cm ↔ feet and inches, kg ↔ lbs).
- Cooking with recipes from another country (cups, tablespoons, ml, grams, ounces).
- Reading weather and oven temperatures in Celsius or Fahrenheit.
- Property sizes in square feet, square metres, acres and hectares.
- File sizes (MB ↔ GB), fuel economy (mpg ↔ L/100 km) and tyre pressure (psi ↔ bar).
Tips for better results
- US and UK gallons and pints differ by about 20% — check which one a recipe or car manual uses.
- Temperature is not a simple multiplication: use the formula shown (°F = °C × 9/5 + 32).
- Storage makers use 1 GB = 1,000 MB, while some operating systems show GiB (1,024 MiB) — both are listed.
How to use the Unit Converter
- Choose the measurement, such as length or temperature.
- Enter the value and pick the units to convert from and to.
- Read the result, the value in every other unit and the conversion chart below.
Frequently asked questions
How do I convert millimetres to inches?
To convert millimetres to inches, divide by 25.4. For example, 10 mm = 0.393701 in.
How do I convert inches back to millimetres?
Press the swap button between the units. 1 in = 25.4 mm.
Is the conversion exact?
Yes. It uses the official definitions of the units; results are only rounded to six significant digits for display.
Are the conversions exact?
Yes. Units are converted with their defined factors — for example 1 inch is exactly 2.54 cm and 1 pound is exactly 0.45359237 kg — and results are rounded to six significant digits only for display.
Are cups and gallons US or UK?
Cups, pints, quarts and gallons are US customary units unless marked UK. UK (imperial) gallons and pints are listed separately because they are about 20% larger.
How many centimetres are in an inch?
Exactly 2.54 cm. To convert inches to centimetres, multiply by 2.54; to convert centimetres to inches, divide by 2.54.
How do I convert kilograms to pounds?
Multiply by 2.20462 (1 kg = 2.20462 lb). To convert pounds to kilograms, multiply by 0.453592.