Unit Converter Free Online
Convert between units of length, weight, temperature, area, volume, speed and data storage instantly. Type a number and see every conversion at once. No install, no sign-up, no upload. All calculations run locally in your browser. Includes pyeong (Korean area unit) and all common metric and imperial units.
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When to use it
Know how big a Korean apartment really is
On the "Area" tab, type 84, pick m² on the left and "pyeong" on the right: about 25.4 pyeong. Going the other way, 25 pyeong is about 82.6 m².
Check a TV or a package from overseas
On "Length", 55 inches is about 139.7 cm. On "Weight", 150 pounds is about 68 kg. The rest of the units on the same tab are listed below your result.
Convert a race distance and a temperature
26.2 miles is about 42.2 km. On "Temperature", 98.6 °F comes out as 37 °C.
How to use
- Click a category tab: Length, Weight, Temperature, Area, Volume, Speed or Data.
- Enter a number in the input field. Select the source unit on the left and the target unit on the right.
- The converted value appears instantly. All other unit conversions for the same category are listed below for quick reference.
How it works
Each category defines units with a conversion factor relative to a base unit (meters for length, kilograms for weight, etc.). Your input is multiplied by the source factor to get the base value, then divided by the target factor. Temperature uses the standard Celsius/Fahrenheit/Kelvin formulas instead of simple multiplication. All arithmetic runs in JavaScript using 64-bit floating-point numbers, providing at least 15 digits of precision. Nothing is uploaded or tracked.
FAQ
What units can I convert?
Length (mm, cm, m, km, inch, foot, yard, mile), Weight (mg, g, kg, tonne, oz, lb, stone), Temperature (°C, °F, K), Area (mm² to km², acre, pyeong), Volume (mL, L, m³, gallon, quart, fl oz, cup), Speed (m/s, km/h, mph, knot, ft/s), and Data (B, KB, MB, GB, TB, bit, Kbit, Mbit).
How accurate are the conversions?
Conversions use standard conversion factors and JavaScript's 64-bit floating-point arithmetic, giving precision to at least 8 significant digits for display. This is accurate enough for everyday and most professional use.
Is this tool free?
Yes, completely free. It runs entirely in your browser with no sign-up, no install and no data sent to any server.
Can I convert temperature?
Yes. Temperature conversion between Celsius, Fahrenheit and Kelvin uses the standard formulas (not simple multiplication), so results are always correct. For example, 0°C = 32°F = 273.15 K.
What is a pyeong?
Pyeong (평) is a traditional Korean unit of area equal to about 3.306 m² (roughly 35.6 ft²). It is commonly used in Korean real estate listings.
How many bytes is 1 KB here?
1 KB is counted as 1,024 bytes, and MB, GB and TB step up by 1,024 each.
Can I convert currency or time?
No. It converts seven kinds of units only: length, weight, temperature, area, volume, speed and data size.
Are there traditional Korean units besides pyeong?
No. Pyeong is the only Korean unit, found under area. Other measures such as geun or don are not included.
Last checked: October 9, 2026 · Dagochim team