Length Converter
Convert between inches, feet, yards, miles, millimeters, centimeters, meters, and kilometers.
What is Length Converter?
The length converter switches any length between U.S. customary (inches, feet, yards, miles) and metric (mm, cm, m, km) units. All eight units are shown side-by-side at once — no need to run multiple conversions.
Formula
All conversions go through the SI base unit (meters) using exact conversion factors:
- 1 in = 0.0254 m (exact, by international agreement)
- 1 ft = 0.3048 m, 1 yd = 0.9144 m, 1 mi = 1,609.344 m
- 1 mm = 0.001 m, 1 cm = 0.01 m, 1 km = 1,000 m
Worked example
Convert 10 feet to other units:
- = 120 inches
- = 3.333 yards
- = 0.001894 miles
- = 3.048 m
- = 304.8 cm
How to use this calculator
- Type the number you want to convert.
- Pick the unit it is in.
- All other units appear at once — pick the one you need.
Frequently asked questions
Is 1 inch exactly 2.54 cm?
Yes, since 1959 by international agreement. The U.S., UK, and Canada all adopted this exact definition to replace earlier slightly different values.
What about nautical miles?
Not included — this converter handles U.S. customary and metric land units only. 1 nautical mile = 1,852 m = 1.15078 statute miles.
Why are miles so ugly to convert?
The U.S. "statute" mile derives from 5,280 feet. That odd number comes from the Roman mile (mille passus = 1,000 double paces), modified by Queen Elizabeth I in 1593.
Is the result always exact?
Multiplications are exact up to floating-point precision (about 15 digits). Results are displayed rounded to sensible decimals.