Energy converter
Convert joules, calories, kcal, Wh, kWh and BTU.
How the calculation works
Energy has many units because it shows up in physics, nutrition, electricity bills and air conditioning. The conversion goes through the joule (J).
Equivalences
- 1 kJ = 1,000 J · 1 kcal = 4,184 J
- 1 Wh = 3,600 J · 1 kWh = 3,600,000 J
- 1 BTU ≈ 1,055 J
Food "calories"
The "calorie" on food labels is actually the kilocalorie (kcal): a "200-calorie" bar is 200 kcal.
kWh: the electricity-bill unit
A 1,000 W device running for 1 hour uses 1 kWh — the basis of your power bill.
Examples
- 1 kWh = 3.6 million joules = 860 kcal.
- 500 kcal = 2,092 kJ (500 × 4.184).
Frequently asked questions
Are calorie and kilocalorie the same?
No. 1 kcal = 1,000 cal. The food "calorie" is really the kilocalorie.
What is 1 kWh?
The energy of a 1,000 W device running for 1 hour — the unit on your power bill.
What does BTU mean in air conditioners?
It is the cooling capacity per hour. More BTUs cool a larger room.
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Updated on June 17, 2026 · by Rafael Rossi · Methodology & sources