Length Converter
Convert metric, imperial, navigation, and scientific length units with live results, accurate formulas, and reference tables.
Length conversion
Calculator
Results update instantly. Use Calculate to confirm the current conversion.
Result
1 in ≈ 25.4 mm
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Popular length conversions
Open a focused converter for a commonly searched length conversion.
Conversion table
Common inches to millimeters values, generated from the selected units.
| inches (in) | millimeters (mm) |
|---|---|
| 1 inch | 25.4 millimeters |
| 5 inches | 127 millimeters |
| 10 inches | 254 millimeters |
| 20 inches | 508 millimeters |
| 50 inches | 1,270 millimeters |
| 100 inches | 2,540 millimeters |
Formula
Multiply the value in inches by 25.4 to get millimeters.
mm = in × 25.4Example
Convert 1 inch:
1 in ≈ 25.4 mm1 inch is approximately 25.4 millimeters.
Unit information
Concise reference information for the selected source and target units.
Inch (in)
Imperial- Definition
- One international inch equals exactly 25.4 millimeters.
- Usage
- Common in the United States and for screens, hardware, and construction materials.
Millimeter (mm)
Metric- Definition
- One millimeter is one-thousandth of a meter.
- Usage
- Used for precise dimensions, manufacturing, medicine, and rainfall.
Frequently asked questions
Which length units does this converter support?
The converter supports 14 units: millimeters, centimeters, meters, kilometers, inches, feet, yards, miles, nautical miles, micrometers, nanometers, light years, astronomical units, and parsecs.
How does the length converter calculate results?
Each value is converted to meters as a shared base unit, then converted from meters to the selected target unit.
Can the converter handle decimals, negative values, and zero?
Yes. The input accepts integers, decimals, negative values, and zero, and updates the result immediately.