Convert between length, weight, temperature, area, volume, and speed units instantly as you type. Includes a quick-reference table of the most common conversions for whichever category you're working in.
| 1 inch = 2.54 cm |
| 1 foot = 30.48 cm |
| 1 yard = 0.9144 m |
| 1 mile = 1.60934 km |
| 1 meter = 3.28084 ft |
| 1 kilometer = 0.621371 mi |
Every unit within a given category (length, weight, area, and so on) measures the same underlying physical quantity, just using a different-sized reference scale — a meter and a foot both measure length, they just define 'one unit' differently. Converting between them means expressing a value from one scale in terms of the other, which for most categories is a straightforward multiplication by a fixed conversion factor: this tool converts every value through a common internal 'base unit' per category (meters for length, kilograms for weight, and so on), multiplying into the base unit and then dividing back out into your target unit, which keeps the conversion logic consistent and accurate across every possible unit pairing within a category.
Most of the world uses the metric system (meters, kilograms, liters, and their prefixed variants like kilometers and milligrams) as the standard measurement system for everyday life, science, and industry, while the United States continues to primarily use a US customary system (inches, feet, pounds, gallons) descended from the British imperial system, with the UK itself now using a mix of both depending on context. This tool includes both metric and imperial/US customary units side by side within each category specifically so you can convert freely between the two systems, which is one of the most common real-world reasons to need a unit converter at all.
Unlike every other category in this tool, temperature scales don't share a common zero point, which means converting between them can't be done with simple multiplication the way converting meters to feet can. Celsius sets zero at water's freezing point, Fahrenheit sets zero at a different reference entirely (originally based on a brine solution), and Kelvin sets zero at absolute zero, the theoretical point of no thermal energy — converting between any two requires the correct linear formula (a multiplication and an offset together) specific to that pair of scales, which this tool applies internally so you never need to remember the formulas yourself.
Different fields and regions have strong conventions about which unit to use for a given kind of measurement — cooking recipes commonly use cups and fluid ounces in the US but milliliters and grams elsewhere, real estate listings might use square feet in the US but square meters in much of the rest of the world, and road signage uses miles in the US and UK but kilometers almost everywhere else. Rather than trying to remember every regional convention, a unit converter lets you work naturally in whichever unit you're most comfortable with and translate the result into whatever unit your audience, tool, or document actually expects.
Unit conversion comes up constantly in practical contexts: adjusting a recipe between metric and US measurements, converting a travel distance or speed limit when crossing between countries with different measurement systems, converting body weight or height between kilograms/centimeters and pounds/feet-and-inches for medical or fitness tracking, converting a property's area between square feet and square meters when comparing international real estate listings, and converting a shipment's weight or volume between systems for international logistics and customs documentation.
Unit Converter handles everyday measurement conversions. These related calculators cover other common everyday and financial math.