Unit Converter

Unit conversion is one of the most common everyday calculations: cooking from a recipe in different units, planning international travel, doing science homework, comparing fuel economy or just understanding a measurement from another country. This tool covers the six categories most people need: length, weight, temperature, area, volume and speed.

Length includes both metric (meter, centimeter, kilometer) and imperial (inch, foot, yard, mile) units. Weight covers kilograms, grams, pounds, ounces, stones and metric tons. Temperature converts between Celsius, Fahrenheit and Kelvin — useful for everything from oven settings to chemistry. Volume includes liters and milliliters along with US gallons, quarts, pints and cups.

For temperature, remember that conversions are not just multiplication: Celsius and Fahrenheit have different zero points, so the formula is F = C × 9/5 + 32. Kelvin shares the Celsius scale but starts at absolute zero (−273.15 °C). The calculator handles all this for you automatically.

Switch tabs to change category, choose your source and destination units, and type any value. The conversion happens instantly, and the swap button flips the direction. All conversions use internationally standardized factors so you can rely on the results for school, work or travel.

The metric system, formally the International System of Units (SI), is used by 95% of the world's population and almost all scientific work. The United States, Liberia and Myanmar remain the only countries still using imperial units (or US customary units, which differ slightly) for everyday measures. This converter handles both systems and also covers the older units (acres, miles per hour, Fahrenheit) that still dominate American commerce and conversation.

Temperature conversions are non-linear because the scales have different zero points as well as different sized degrees. Fahrenheit to Celsius is (°F − 32) × 5/9; Celsius to Kelvin is °C + 273.15. Absolute zero is 0 K or −273.15 °C or −459.67 °F. Cooking, weather and health contexts almost always use Celsius or Fahrenheit, while scientific work uses Kelvin to avoid negative temperatures and make ratios meaningful.

Cooking conversions trip up almost every home cook at some point. A US cup is 240 ml, a metric cup is 250 ml, an Australian cup is 250 ml, and a Japanese cup is 200 ml. A US tablespoon is 14.79 ml, an Australian tablespoon is 20 ml. For most recipes the difference is tolerable, but in baking — where ratios matter — use weight (grams) rather than volume whenever possible for repeatable results.

Engineering and construction often require conversion between very different size scales. A square meter is about 10.76 square feet, a hectare is about 2.47 acres, and a square kilometer is roughly 247 acres or 100 hectares. Volume conversions can be even less intuitive: a cubic meter holds 1,000 liters, but a metric ton of water has a volume of exactly one cubic meter, while a metric ton of steel takes up only about 0.13 cubic meters. Always check the density of the substance when converting between mass and volume.