Free Unit Converter

Use this free unit converter for length, weight, temperature, area, volume, speed, data, time, pressure and energy. Pick a category, choose two units and see the result as you type.

Value

From

Result

3.280839895 Foot

How to Convert Units

Pick a category.

Tap one of the 10 tabs, such as Length or Temperature. The tool starts with the first two units of that category and a value of 1.

Choose your units.

Open From and To and type part of a name or symbol to filter the list. Picking the same unit on both sides switches the other one.

Type the value.

The result updates as you type, and the copy button puts it on your clipboard. Swap flips the direction, but retype the number if the result was 1,000 or more.

Frequently Asked Questions

Answers about units, accuracy, data sizes, formulas and the swap button.

What units can this converter handle?

It handles 94 units in 10 categories: length 13, weight 10, temperature 4, area 10, volume 14, speed 6, digital storage 10, time 10, pressure 8 and energy 9. Each category mixes metric units with US or imperial ones, such as acres, stones and knots.

How do I convert cm to inches?

Divide centimetres by 2.54, since one inch is exactly 2.54 cm. So 30 cm is about 11.81 inches. In the tool, pick Length, set From to Centimetre and To to Inch, then type the number.

How do I convert Celsius to Fahrenheit?

Multiply by 9/5 and add 32. So 25 °C is 77 °F and 100 °C is 212 °F. Going the other way, subtract 32 and multiply by 5/9. The scales meet at −40, and Kelvin is Celsius plus 273.15.

How many MB are in a GB?

This tool counts 1,024 MB in a GB, the binary size often used for memory. Drive makers and most cloud plans use 1,000. Here KB and KiB give the same result, so for 1,000-based sizes, multiply or divide by 1,000 yourself.

How accurate are the conversions?

Common factors are exact by definition, such as 1 inch = 2.54 cm, 1 lb = 0.45359237 kg and 1 mile = 1,609.344 m. A few are rounded, such as light year, astronomical unit, knot, psi and BTU, and Mach is fixed at 343 m/s. Results show up to 10 significant figures.

Why is the number wrong after I swap units?

Swap puts the result in the value box with its thousands separator, such as 1,609.344, and the converter then reads only the part before the comma. For results of 1,000 or more, retype the number after you swap.

How long is a month or a year in the time converter?

A month is fixed at 30 days and a year at 365 days, with no leap years. So 1 year shows as 365 days and 12 months as 360 days. For calendar math between real dates, these fixed lengths will be slightly off.

Which cup, gallon and ounce does it use?

Cups, pints, quarts, fluid ounces, tablespoons and teaspoons are US measures. Gallons come in both US (3.785 L) and UK (4.546 L) versions. The weight ounce is the standard 28.35 g ounce, and stone and long ton are also listed.

Does it show the conversion formula?

No. The tool shows the result only, not the formula or the steps. To see a factor, convert 1 of the first unit; for example, 1 foot shows 0.3048 metres. Temperature is the exception, since it adds an offset as well as a factor.

Can this unit converter convert money?

No. Currency rates change every day, so they sit in a separate tool. Use the Currency Converter, which converts 30 currencies at the European Central Bank's daily reference rates. This unit converter covers physical and digital units only.

Is the unit converter free and private?

Yes. There is no account or usage limit, and each conversion is plain math in your browser, so the numbers you type are not sent or saved. On the live site, Google Analytics counts each change of the From unit, never the numbers you type.

Unit Converter for 10 Kinds of Measurement

94 units for length, weight, temperature, area, volume, speed, data, time, pressure and energy, with results that update as you type.

Unit converter results: 1 in = 2.54 cm, 1 kg = 2.204622622 lb, 1 gal = 3.785411784 L and 1 ac = 4,046.856422 m²

Convert Metric and Imperial Units

Switch between metres and feet, kilograms and pounds, litres and US gallons, or hectares and acres. Factors such as 1 inch = 2.54 cm and 1 lb = 0.45359237 kg are the exact defined values.

13 length and 10 weight units
Both US and UK gallons
Exact inch, foot and pound factors

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Unit converter turning 100 °C into 212 °F next to a thermometer marked −40, 0, 37 and 100 °C with 373.15 K and 671.67 °R

Convert Celsius, Fahrenheit and Kelvin

Temperature uses formulas, not a single factor, so 100 °C gives 212 °F and −40 is the same on both scales. Rankine is included, and values below absolute zero are not blocked.

Four scales: °C, °F, K and °R
100 °C shows as 212 °F
Negative temperatures are allowed

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Data Storage Uses 1,024 Steps

In this tool 1 KB is 1,024 bytes and 1 GB is 1,024 MB, so KB and KiB give the same answer. For the 1,000-based sizes on drive labels, multiply by 1,000 yourself.

Results Update as You Type

There is no Convert button. Each key you press recalculates the result, shown to up to 10 significant figures, and very large or tiny values switch to scientific notation.

Science and Engineering Units

Pressure covers Pa, kPa, bar, atm, psi, mmHg and inHg. Energy covers joules, calories, kWh, BTU and electronvolts, and length reaches light years and astronomical units.

Free, Private, No Sign-Up

Use it without an account or a limit. Every conversion is plain math in your browser, so the numbers you enter are never sent anywhere or saved.

Who Uses a Unit Converter?

Students, travelers, cooks and builders all switch between metric and imperial units.

Students & Scientists

Convert between SI and imperial units for physics, chemistry and engineering homework, from joules to calories or pascals to psi. Check results against your own working before you hand them in.

Metres, feet and light years for physics problems
Pascals, bar and psi for pressure questions
Joules, calories and kWh for energy work

Travelers & Expats

Read speed limits, weather and luggage weights when you live in or visit a country that uses other units. Pick the two units once and type each new number.

mph to km/h for road speed limits
°F to °C for weather forecasts
Pounds to kilograms for checked luggage limits

Cooking & DIY

Follow a recipe or plan a home project when the measures don't match your tools. US cups, tablespoons and teaspoons sit next to millilitres and litres.