Unit Converter — Length, Weight, Temperature, Clothing Sizes & Cooking Measures
Change one value and every other unit updates at once. Clothing sizes and cooking measures are on the same screen.
How to use
Clothing sizes and cooking measures are in the tabs on the right.
How the unit converter works
This unit converter keeps every box in a category in sync. Type a number into any field, such as 5 feet, and the rest of the fields (inches, centimeters, meters, yards and more) fill in at the same moment, with no “convert” button to press. There are seven standard categories (length, weight, temperature, area, volume, speed and data) and two practical extras: a clothing-size converter for Korea, the US and Europe, and a cooking converter that turns cups and spoons into grams and milliliters for common baking ingredients.
How the conversions are calculated
Every category works through one base unit. Your number is first converted into that base unit, then divided by each other unit’s factor. For length the base is the meter, so feet to inches goes feet → meters → inches. This is why the results always agree with each other, no matter which box you typed in. Temperature is the one exception because the scales do not share a zero point, so it uses formulas instead of a single multiplier:
°F = °C × 9/5 + 32 | °C = (°F − 32) × 5/9 | K = °C + 273.15
The factors come from the official definitions. Since the international agreement of 1959, one inch is exactly 2.54 centimeters, one yard is exactly 0.9144 meters, and one pound is exactly 0.45359237 kilograms. A US gallon is exactly 3.785411784 liters. Results are shown to eight significant digits, and very large or very small values switch to scientific notation so they stay readable.
Conversions people look up most
- Inches to centimeters: multiply by 2.54. A 6-foot (72 in) person is 182.9 cm tall.
- Pounds to kilograms: multiply by 0.4536. A 150 lb adult weighs about 68 kg.
- Miles to kilometers: multiply by 1.609. A marathon, 26.2 miles, is 42.2 km.
- Fahrenheit to Celsius: body temperature of 98.6°F is 37°C, a 350°F oven is about 177°C, and water boils at 212°F or 100°C at sea level. The two scales meet at −40.
- Gallons to liters: multiply by 3.785. A 15-gallon fuel tank holds about 57 liters.
US customary, imperial and metric are not the same
The United States, Liberia and Myanmar are the best-known places that have not fully adopted the metric system for everyday use, and even among English-speaking countries the old units differ. A US gallon is 3.785 liters but a UK (imperial) gallon is 4.546 liters. A US pint is 473 mL while a UK pint is 568 mL. The volume units on this page (cups, tablespoons, teaspoons, fluid ounces, pints, quarts and gallons) are all US customary, so they will match an American recipe or a US nutrition label, but not an old British cookbook. A mix-up like this is not just a kitchen problem: in 1999 NASA lost the Mars Climate Orbiter because one team’s software produced thrust values in pound-force seconds while the other expected newton seconds.
Cooking tab: why cups and grams do not convert on their own
A cup measures volume and a gram measures mass, so you can only convert between them if you know how dense the ingredient is. A cup of water weighs about 237 g, a cup of all-purpose flour about 125 g, and a cup of granulated sugar about 200 g. The cooking tab stores a typical density for nine common ingredients and uses the US cup (236.6 mL), tablespoon (14.8 mL) and teaspoon (4.9 mL). These are reference values: flour that has been sifted or packed can differ by 10 percent or more. For bread and pastry, weighing ingredients is far more reliable than scooping.
Clothing and shoe sizes
The clothing tab maps Korean, US and European sizes for men’s and women’s tops, bottoms and shoes. It is built for shoppers buying from Korean brands. Korean women’s tops use the 44, 55, 66, 77 numbering system, men’s tops use chest-based sizes such as 95 and 100, and Korean shoe sizes are the foot length in millimeters (260 for about a US men’s 8). Treat any size chart as a starting point. Every brand cuts differently, so compare your own measurements with the seller’s size chart before ordering.
Data units: why a 1 TB drive shows less space
This converter uses binary units, where 1 KB is 1,024 bytes, 1 MB is 1,024 KB and so on. Storage manufacturers usually count in thousands, so a drive sold as 1 TB holds 1,000,000,000,000 bytes, which an operating system using binary units reports as roughly 931 GB. Neither is wrong; they are different definitions. If you need the decimal version, divide by 1,000 at each step instead of 1,024.
Frequently asked questions
How many centimeters are in an inch?
Exactly 2.54. This is a definition rather than a measurement, set by the international yard and pound agreement of 1959, so inch-to-centimeter conversions are exact. To convert centimeters to inches, divide by 2.54.
Is a US cup the same as a metric cup?
Not quite. A US customary cup is 236.6 mL, the cup on US nutrition labels is rounded to 240 mL, and the metric cup used in Australia and New Zealand is 250 mL. For most recipes the difference is small, but in baking it can change the result, so follow the measuring system the recipe was written in or switch to grams.
How do I convert Fahrenheit to Celsius in my head?
Subtract 30 and halve it for a quick estimate: 80°F gives about 25°C. For an exact answer subtract 32 and multiply by 5/9. The estimate drifts at the extremes, so use the converter for anything important such as food safety temperatures.
Why can I not enter a negative number for length or weight?
Length, weight, area, volume, speed and data amounts cannot be below zero, so the tool asks for a value of 0 or more. Temperature is the exception, since values below zero are normal, but it stops you at absolute zero (−273.15°C), which is the lowest temperature that can exist.
How accurate are the clothing size conversions?
They are typical equivalents, not guarantees. Sizing varies by brand, cut and fabric stretch, and Korean sizes are often cut slimmer than US sizes of the same label. Use the table to narrow your choice, then check the seller’s own measurements.
What is a stone, and who uses it?
A stone is a British unit of weight equal to 14 pounds (6.35 kg). It is still the usual way to state body weight in the UK and Ireland, for example “11 stone 4”. It is not used in the United States.
Does this converter store or send my numbers anywhere?
No. All calculations are done by your browser. Nothing you type is uploaded or saved.