Length Converter
Convert meters (m), kilometers (km), centimeters (cm), millimeters (mm), micrometers, nanometers, inches (in), feet (ft), yards (yd), miles (mi), nautical miles (nmi) and light-years (ly).
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About This Converter
This converter handles 12 units from nanometers to light-years, using exact definitions from NIST and ISO standards. Type a value in any unit and see all others update instantly -- useful for engineering, science homework, or everyday tasks like converting feet to meters for a recipe or travel distance. Imperial-to-metric factors such as 1 inch = 25.4 mm and 1 mile = 1,609.344 m are built in with full precision.
FAQ
Exact inch/foot conversions?
By definition: 1 in = 25.4 mm exactly; 1 ft = 0.3048 m exactly.
Why nautical miles?
Nautical miles (nmi) are used in aviation and maritime contexts and equal 1852 m exactly.
How big is a light-year?
1 light-year is the distance light travels in a vacuum in one year: 9.460 730 472 580.8 km (exact via defined c and Julian year).
Tips for entering values
Select the unit first, then enter a value once — all tiles update instantly. Use scientific notation for very large/small values.