Unit converter
Length, weight, area, volume, temperature, speed, pressure, energy, data and time — converted into every unit in the family at once.
Enter one value and it is converted into every unit of the same kind, because what you usually want is not one answer but a sense of the size. The factors come from the SI and from Korea's Act on Measurement, and the Korean units still used in markets — geun, don, pyeong — are included even though they are not statutory.
What are you converting
What you enter is saved in this browser, so it is still here next time
Every unit of the kind you pick is shown at once
Converted
| Unit | Value |
|---|---|
| Millimetre (mm) | 1,000 |
| Centimetre (cm) | 100 |
| Metre (m) | 1 |
| Kilometre (km) | 0.001 |
| Inch (in) | 39.3701 |
| Foot (ft) | 3.2808 |
| Yard (yd) | 1.0936 |
| Mile (mi) | 0.00062137 |
| Nautical mile (nmi) | 0.00053996 |
Geun, don, pyeong and doe are not statutory units under Korea's Act on Measurement, Article 6. They cannot be used in trade or certification, but markets still use them, so they are included here.
Every conversion passes through one base unit
Each kind has a base — metres for length, kilograms for weight, bytes for data. The value is converted to the base first and then divided out into every unit in the table. 100 cm becomes 1 m, and that becomes 39.3701 inches (÷ 0.0254) and 0.00062137 miles (÷ 1,609.344) in the same table. The number of decimals follows the size of the value, and at a trillion or more or under a millionth the display switches to exponent form.
Pyeong, doe and mal use these values
One pyeong is kept as the fraction 400 ÷ 121 m². Shortening it to 3.3058 already drifts at 100 pyeong — 100 pyeong is 330.5785 m² and 33 m² is 9.9825 pyeong. One doe is 1.8039 L and one mal is ten of those, 18.039 L. The cup is the Korean measuring cup of 200 mL; fluid ounce, quart and gallon are US units, so a gallon is 3.7854 L.
Why time has no months or years
A month is 28 to 31 days and a year 365 or 366, so neither can be fixed in seconds. Time therefore runs from milliseconds to weeks (604,800 s). Data goes the other way and puts the 1,000 and 1,024 series side by side — 1 TB shows as 931.3226 GiB, and that 5% is why the disk box and the operating system disagree.
Common questions
QAre the inch and pound figures exact?
Yes. The 1959 international yard and pound agreement fixed the inch at exactly 25.4 mm and the pound at exactly 0.45359237 kg. These are definitions rather than measurements, so no rounding error creeps in.
QWhy do I see a geun as both 600 g and 375 g?
It depends on what is being sold. Meat and vegetables go by 600 g, fruit and herbal medicine by 375 g (100 don). This converter uses 600 g. Geun, don and pyeong are not statutory units in Korea — using them in trade breaches the Act on Measurement — but markets use them anyway.
QWhy is temperature handled differently?
Other units share a zero, so converting is a single multiplication. Celsius and Fahrenheit put zero in different places, so you multiply and then add: °F = °C × 1.8 + 32. It is why twice 20°C is not 40°C in any meaningful sense.
QHow many knots is 100 km/h?
53.9957 knots. A knot is one nautical mile (1,852 m) per hour, or 0.51444 m/s, and 100 km/h is 27.7778 m/s. The same value also appears as 62.1371 mph.
QHow many mmHg is one atmosphere?
Exactly 760 mmHg. One atmosphere is defined as 101,325 Pa and one mmHg is set at 1/760 of that. In psi it is 14.6959, in bar 1.01325.