How it works
Convert energy between the SI joule and units used for electricity bills (kilowatt-hours), heating fuel (BTU and therms), food (kilocalories) and physics (electronvolts).
One kilowatt-hour is exactly 3.6 million joules. The calorie used here is the thermochemical calorie of exactly 4.184 J; a food "Calorie" is a kilocalorie. The BTU is the International Table BTU (1,055.05585262 J), and the US therm used on gas bills is 105,480,400 J, roughly 100,000 BTU.
Formula
Result = value × (J per from-unit) ÷ (J per to-unit). 1 kWh = 3,600,000 J; 1 kcal = 4,184 J.
Questions people ask
How many BTU are in a kilowatt-hour?
About 3,412.14 BTU. This is useful when comparing electric and gas heating costs.
Is a food Calorie the same as a calorie?
No. A food Calorie (capital C) is 1,000 calories, or one kilocalorie, which is 4.184 kJ. Food labels outside the US often list kilojoules.
How many kWh are in a therm?
About 29.3 kWh. Gas utilities bill in therms or in hundreds of cubic feet (CCF), and one CCF of natural gas is roughly one therm.