About this tool
Convert an energy amount between ten units, fully client-side in your browser. Choose the From and To units, enter a value, and read the converted result live; use ⇄ to swap the two units.
The base unit is the joule (J). Your value is multiplied by the From factor to reach joules, then divided by the To factor. For instance 1 kWh = 3.6 million joules and 1 BTU = 1055.05585 J, so 1 kWh = 3.6e6 / 1055.05585 ≈ 3412.14 BTU.
Handy for physics, nutrition, heating and electricity bills. Note the food Calorie (capital C) equals one kilocalorie = 4184 J, and the tiny electronvolt (1 eV = 1.602176634e-19 J) is included for atomic-scale work, so results can appear in scientific notation.
Frequently asked questions
What is the base unit?
The joule (J). Every unit carries an exact factor to joules, and conversions go value × from-factor ÷ to-factor.
How much is 1 kWh in BTU?
One kilowatt-hour is 3,600,000 J, which divided by 1055.05585 J per BTU is about 3412.14 BTU.
Is a Calorie the same as a calorie?
No. The lowercase calorie is 4.184 J; the food Calorie is a kilocalorie, 4184 J. This tool lists both separately.
Why do some results look like 6.2e18?
Because the electronvolt is astronomically small, converting large energies into eV yields huge numbers shown in scientific notation.