Energy Converter
Convert energy units: joules, kilojoules, kilowatt-hours (kWh), calories, kilocalories (kcal/Calories), and British Thermal Units (BTU).
How Energy Converter works
Joule — the SI unit of energy
The joule is the SI unit of energy. 1 joule = 1 watt × 1 second. Common multiples: 1 kJ = 1,000 J; 1 MJ = 1,000,000 J.
kWh — electricity and gas billing
1 kWh = 3,600,000 joules (3.6 MJ). Energy bills in the UK are in kWh. 1 kWh of electricity at the current Ofgem cap costs approximately 24.5p.
Calories and kilocalories
The dietary "Calorie" (capital C) is actually a kilocalorie (kcal): 1 kcal = 1,000 cal = 4,184 J. Food energy is measured in kcal. A chocolate bar with 250 kcal provides 1,046 kJ of energy.
Frequently asked questions
How many joules in a kWh?
1 kWh = 3,600,000 joules (3.6 MJ). Derived from 1,000 watts × 3,600 seconds.
What is the difference between a calorie and a kilocalorie?
A kilocalorie (kcal) = 1,000 calories (cal). Food labels and dietary advice use kcal, often written as "Calories" with a capital C to distinguish from the small calorie.
How many kWh is 1 BTU?
1 BTU = 0.000293071 kWh. Or 1 kWh = 3,412.14 BTU. BTU is commonly used for heating and air conditioning capacity in the US.
How many calories in a joule?
1 joule = 0.239006 calories. 1 calorie = 4.184 joules.
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