Length Converter
Convert between meters, feet, inches, miles, kilometers, and more.
Length converter
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How It Works
This converter works by converting any input value to a base unit (meters) first, then dividing by the target unit's factor. Key reference points: 1 inch = 2.54 cm (exact by international definition), 1 foot = 30.48 cm, 1 yard = 0.9144 m, and 1 mile = 1.609344 km. Nautical miles (1,852 m) are based on Earth's geometry and used in navigation.
Because all conversions pass through meters, the tool can convert between any pair of units with a single multiplication and division — no complex lookup tables needed.
Tips & Best Practices
Frequently Asked Questions
How many centimeters are in an inch?
One inch equals exactly 2.54 centimeters. This is an exact definition established by international agreement in 1959. To convert inches to cm, multiply by 2.54; to convert cm to inches, divide by 2.54.
How do I convert kilometers to miles?
Multiply kilometers by 0.621371 to get miles, or divide miles by 0.621371 to get kilometers. A quick approximation: multiply km by 0.6 for a rough mile equivalent. For example, 10 km ≈ 6.2 miles.
What is a nautical mile?
A nautical mile equals 1,852 meters (about 1.151 regular miles). It is based on the circumference of the Earth — one nautical mile corresponds to one minute of latitude. It is standard in maritime and aviation navigation.
What is the difference between metric and imperial systems?
The metric system (meters, kilograms, liters) is based on powers of 10 and used in most countries. The imperial system (feet, pounds, gallons) developed historically in Britain and is still used primarily in the United States.
Why does the US still use the imperial system?
The US retains the imperial system largely due to historical inertia and the cost of conversion. Congress authorized metric use in 1866 and made it the preferred system in 1975, but adoption has been voluntary. Industries like science, medicine, and the military already use metric, while everyday life remains largely imperial.
What is the difference between a nautical mile and a regular mile?
A regular (statute) mile is 5,280 feet (1,609.344 meters), while a nautical mile is 6,076 feet (1,852 meters) — about 15% longer. The nautical mile is based on Earth's geometry (one minute of latitude), making it natural for navigation.
How tall is 180 cm in feet and inches?
180 cm equals approximately 5 feet 10.87 inches, or roughly 5'11". To convert: divide 180 by 2.54 to get 70.87 inches, then divide by 12 to get 5 feet with 10.87 inches remaining.
What is the smallest and largest unit of length?
The Planck length (~1.6 × 10⁻³⁵ m) is the smallest meaningful length in physics. The largest practical unit is the parsec (3.26 light-years) used in astronomy. SI prefixes extend from yoctometer (10⁻²⁴ m) to yottameter (10²⁴ m).
How are astronomical distances measured?
Astronomers use astronomical units (AU, Earth-to-Sun distance ≈ 150 million km) for the solar system, light-years (9.46 trillion km) for nearby stars, and parsecs (3.26 light-years) for galaxies. Each unit suits a different scale of the universe.
How accurate are length conversions?
Conversions between metric units are exact (based on powers of 10). The inch-to-centimeter factor (2.54) is also exact by international definition since 1959. Most other imperial-to-metric factors are exact or defined to many decimal places, so rounding is the only source of error.