About this tool
Most unit conversions are one multiplication, and the reason people still get them wrong is that the factor they half-remember is a rounded one. A foot is not 0.3 metres and a pound is not 0.45 kilograms. This uses the exact defined values, which costs nothing and means a long conversion chain does not drift.
Temperature is the exception, and it is the one worth understanding. Celsius, Fahrenheit and Kelvin have different zero points, so you cannot convert between them with a multiplier the way you can with metres and feet. The tool converts your value into Celsius first and then out into whatever you asked for, and it stops if the answer would fall below absolute zero, because no real measurement does.
Regional land measures are deliberately absent. A bigha means one thing in one district and something else two districts over, so a single conversion factor would quietly mislead most of the people who used it. Area sticks to square metres, square feet, acres and hectares, all of which mean the same thing everywhere.
How to use this tool
- Choose the measurement. Length, Weight, Temperature, Area or Volume. Changing it refills both unit lists, so pick this before the units.
- Type the value. Decimals are fine. It opens on 1 metre to kilometres, which is there to show the shape of the form rather than because you needed it.
- Set From and To. The two lists hold the same units. Length covers metres, kilometres, centimetres, millimetres, feet, inches and miles.
- Read the result. The converted number with its unit spelled out, so there is no guessing whether that was feet or inches.
What this tool does not do
- No regional land units — bigha, katha, guntha, cent and marla all vary by place and are left out.
- No tola, ratti or other traditional weights. Weight is kilograms, grams, pounds and ounces.
- No currency, fuel economy, speed, time, pressure or data-size conversions.
- It converts one value at a time. There is no table or bulk list.
Common questions
How accurate are the conversions?
The factors are the exact defined ones, not rounded approximations: a foot is 0.3048 metres, a pound is 0.45359237 kilograms, an acre is 4046.8564224 square metres. Results are shown to eight decimal places, which is more than any of these jobs need.
Is temperature handled differently?
It has to be. Celsius, Fahrenheit and Kelvin are offset scales, not multiples of each other — 20°C is not twice 10°C in any meaningful sense. The conversion goes through Celsius as a pivot rather than multiplying by a factor, and it refuses any value below absolute zero, which is -273.15°C.
Which gallon is it?
The US gallon, 3.785411784 litres. It is not the imperial gallon, which is about a fifth larger. The unit list says US gallons for exactly this reason.
Can it do bigha, katha or guntha?
No, and that is on purpose. A bigha is a different size in Rajasthan, Bihar and West Bengal, and sometimes in neighbouring districts. Giving one number would be wrong for most people using it. Area here is square metres, square feet, acres and hectares.
Why did the unit lists change by themselves?
Switching the measurement reloads them. Feet do not belong in a list of weights, so both dropdowns are rebuilt from whatever measurement is selected.