Length Converter
Convert between 9 length units instantly: mm, cm, m, km, inches, feet, yards, miles, and nautical miles. Free online converter with comparison charts.
About This Calculator
The Length Converter is a free online tool that instantly converts values between nine different length units spanning both the metric system and the imperial/US customary system. Whether you are a student solving physics problems, a construction professional converting blueprint measurements, a traveler comparing distances in different countries, or a DIY enthusiast working on a home project, this converter handles all common length conversions with scientific precision.
The converter supports millimeters (mm), centimeters (cm), meters (m), kilometers (km), inches (in), feet (ft), yards (yd), miles (mi), and nautical miles (nmi). You can convert from any unit to any other unit — for example, kilometers to miles for road distances, inches to centimeters for furniture dimensions, or feet to meters for real estate listings.
How the conversion works
Every conversion uses the meter as the base reference unit. The calculator first converts the input value from the source unit to meters using the standard SI conversion factor, then converts from meters to the target unit. For example, to convert 10 feet to meters: 10 ft × 0.3048 = 3.048 m. To convert back from meters to feet: 3.048 m ÷ 0.3048 = 10 ft.
Metric system
The metric system, officially the International System of Units (SI), is the global standard for measurement. The meter (m) is the base unit of length. Common prefixes include milli- (1/1000), centi- (1/100), and kilo- (1000). One kilometer equals 1,000 meters, one centimeter equals 0.01 meters, and one millimeter equals 0.001 meters.
Imperial and US customary system
The imperial system is used primarily in the United States, Liberia, and Myanmar, while the UK and Canada use a mix of metric and imperial. One inch is defined as exactly 25.4 mm, one foot equals 12 inches (0.3048 m), one yard equals 3 feet (0.9144 m), and one mile equals 5,280 feet (1,609.344 m). The nautical mile (1,852 m) is used in aviation and maritime contexts worldwide.
Regional usage notes
India (IN): India uses the metric system officially. Road distances are in kilometers, fabric and furniture dimensions are commonly in meters and centimeters, and real estate areas are in square feet while plot sizes are often in square meters or acres.
United States (US): The US primarily uses imperial units. Road signs show miles, construction uses feet and inches, and body height is expressed in feet and inches. However, science, medicine, and many engineering fields use metric units.
United Kingdom (UK): The UK uses a mixed system. Road distances are in miles, beer is sold in pints, but most other measurements (including food packaging, science, and education) use metric units. Body weight is often in stone and pounds, while height is in feet and inches.
Frequently Asked Questions
How does the Length Converter work?
Enter a numeric value, select the source unit and target unit from the dropdown menus, and click Convert. The calculator applies the standard conversion factor — converting first to meters as the base unit, then to the target unit — and displays the result along with a bar chart comparing the value across all supported units.
How many length units does the converter support?
The converter supports nine units: millimeter (mm), centimeter (cm), meter (m), kilometer (km), inch (in), foot (ft), yard (yd), mile (mi), and nautical mile (nmi). Both metric and imperial/US customary systems are covered.
How do I convert meters to feet?
One meter equals approximately 3.28084 feet. To convert meters to feet, enter the meter value as the input, select Meters (m) as the source unit and Feet (ft) as the target unit, then click Convert. The result is displayed instantly with four-decimal precision.
How do I convert inches to centimeters?
One inch equals exactly 2.54 centimeters. Enter the inch value, select Inches (in) as the source and Centimeters (cm) as the target, then click Convert. The converter uses the standard 1 in = 2.54 cm conversion factor for all calculations.
Is the conversion accurate for engineering and scientific use?
Yes, all conversions use the internationally accepted standard conversion factors defined by the International System of Units (SI). Meter is the base unit, and every other unit's conversion factor is precise to at least six decimal places, making the results suitable for engineering, construction, and scientific applications.
Does the length converter work offline?
The length converter runs entirely in your browser with no server-side processing required. All conversion factors are built into the application, so once the page loads, conversions happen instantly even without an internet connection.
Can I convert between metric and imperial units?
Yes, the converter supports both metric units (mm, cm, m, km) and imperial/US customary units (in, ft, yard, mile) plus nautical miles. You can mix and match any source and target unit, such as converting kilometers to miles or inches to centimeters.
What is the difference between a nautical mile and a statute mile?
A statute mile (land mile) equals 1,609.344 meters, while a nautical mile equals 1,852 meters (one minute of latitude). Nautical miles are used primarily in aviation and maritime navigation. The converter supports both units for complete flexibility.