Joules, calories, kWh, BTU.
Converts between joules, calories, kilocalories, watt-hours, BTU, and kilojoules.
1 kcal = 4.184 kJ ≈ 4,184 J. Food 'calories' are actually kilocalories (kcal).
This distinction between calories and kilocalories is one of the more commonly misunderstood units in everyday use — nutrition labels use 'Calories' as shorthand for kilocalories, which can cause confusion when comparing against scientific or engineering energy figures.
1,000 J ≈ 239.01 cal.
No — 1 food 'Calorie' (capital C) = 1,000 scientific calories = 1 kilocalorie.
British Thermal Unit — energy to raise 1 lb water by 1 °F. Common in HVAC. 1 BTU ≈ 1,055 J.
A kilowatt-hour is simply a more practically sized unit for household energy use — a joule is tiny by comparison, so kWh avoids working with unwieldy large numbers on a bill.