Length Converter
Length Converter translates a linear measurement among common metric and imperial/US units using fixed factors based on the metre. It supports m, km, cm, mm, in, ft, yd, and mi. The arithmetic changes the unit representation, not the precision or reliability of the original measurement.
Runs locally — files stay on your deviceHow many centimetres are in one inch?
Exactly 2.54 centimetres; the inch is defined as 0.0254 metre.
Linear units scale by one conversion factor
Each supported length maps to metres, then from metres to the destination. For example, 1 ft = 0.3048 m and 1 mi = 1609.344 m.
How it works
Enter a numeric value, choose source and destination units, and select display precision. The tool multiplies by the source factor and divides by the destination factor.
Key concepts
Factors are exact or conventional
The inch-to-metre definition is exact; a measured input still has uncertainty.
Precision is display formatting
Extra decimals do not improve the source measurement.
When to use it
- Translate drawing dimensions.
- Compare metric and imperial distances.
- Convert a measured length for documentation.
When not to use it
- Do not use length units for area or volume.
- Do not report more significant figures than the source supports.
- Do not confuse statute miles with nautical miles.
Worked examples
Inches to centimetres
- Input
12 in- Expected output
30.48 cm
12 × 2.54 = 30.48.
Miles to kilometres
- Input
1 mi- Expected output
1.609344 km
A statute mile is 1609.344 metres.
Metres to feet
- Input
1 m- Expected output
About 3.28084 ft
The result is rounded for display.
Common mistakes
Using a linear factor for square units
Area factors are squared. Correction: Use Area Converter.
Calling miles nautical
This page uses statute miles. Correction: Use a nautical-specific conversion when needed.
Overstating precision
Conversion cannot create measurement accuracy. Correction: Round to appropriate significant figures.
Best practices
- Record unit symbols with values.
- Preserve a sensible number of significant figures.
- Confirm the type of mile or foot required by the domain.
Related operations and differences
Area Converter
Choose Area Converter when you need to convert common metric and imperial areas.; use Length Converter specifically for convert.
Weight Converter
Choose Weight Converter when you need to convert kilograms, pounds, ounces and more.; use Length Converter specifically for convert.
Data Storage Converter
Choose Data Storage Converter when you need to convert decimal and binary storage units.; use Length Converter specifically for convert.
Energy Converter
Choose Energy Converter when you need to convert joules, calories and watt-hours.; use Length Converter specifically for convert.
Fuel Economy Converter
Choose Fuel Economy Converter when you need to convert MPG, L/100 km and km/L.; use Length Converter specifically for convert.
Power Converter
Choose Power Converter when you need to convert watts, kilowatts and horsepower.; use Length Converter specifically for convert.
Limitations and privacy
- No nautical mile, micrometre, or specialized survey units.
- Floating-point and display rounding apply.
- Does not propagate measurement uncertainty.
Values are converted locally in this browser and are not uploaded.
Frequently asked questions
Is one inch exactly 2.54 cm?
Yes.
Which mile is used?
The statute mile.
Does precision improve accuracy?
No.
Can negative lengths be converted?
The arithmetic accepts them, though physical context determines whether they make sense.