Result equals value times the ratio of conversion factors
Length Conversion =
Solution in Other Units
Unit
Value
Meter (m)
1
Centimeter (cm)
100
Millimeter (mm)
1000
Kilometer (km)
0.001
Foot (ft)
3.2808399
Inch (in)
39.370079
Yard (yd)
1.0936133
Mile (mi)
0.00062137119
Decimeter (dm)
10
Dekameter (dam)
0.1
Hectometer (hm)
0.01
Micrometer (µm)
1000000
Nanometer (nm)
1.0000000e+9
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Length Unit Conversion
This converter uses a base-unit factor system where every length unit has a known ratio to the meter.
result = value × (source factor / target factor)
How It Works
This converter uses a base-unit factor system where every length unit has a known ratio to the meter (the SI base unit). All arithmetic is performed with arbitrary-precision BigNumber math.
Example Problem
Convert 100 feet to meters.
100 × 0.3048 = 30.48 m
The factor 0.3048 is exact because one foot is defined as precisely 0.3048 meters.
Key Concepts
Length conversion relies on exact or defined ratios between units and the SI base unit, the meter. International agreements fix these ratios — for example, one inch is exactly 25.4 mm and one foot is exactly 0.3048 m. This converter uses arbitrary-precision BigNumber arithmetic to avoid floating-point rounding errors across the full range from nanometers to light-years.
Applications
Construction: converting between imperial feet/inches and metric meters/centimeters for international projects
Manufacturing: translating engineering drawings between metric and US customary dimensions
Navigation: converting between nautical miles, statute miles, and kilometers for maritime and aviation use
Science: converting astronomical distances (light-years, parsecs) to standard SI units for calculations
Common Mistakes
Confusing statute miles and nautical miles — a nautical mile is 1,852 m while a statute mile is 1,609.344 m, a 15% difference
Rounding intermediate results — converting through multiple units (e.g., yards to feet to meters) accumulates rounding error; convert directly instead
Mixing up survey feet and international feet — the US survey foot (1200/3937 m) differs from the international foot (0.3048 m) by about 2 parts per million, which matters in large-scale land surveys
Frequently Asked Questions
How many feet are in a meter?
One meter equals approximately 3.28084 feet.
What is the difference between a mile and a kilometer?
One mile equals exactly 1.609344 kilometers.
How do I convert inches to centimeters?
Multiply the number of inches by 2.54. This factor is exact by definition.
Related Calculators
Area Converter — convert between square meters, square feet, acres, and more.
Volume Converter — convert between liters, gallons, cubic meters, and more.