Energy Converter
Convert between J, kJ, cal, kcal, Wh, kWh, BTU, and eV — live update.
Frequently asked questions
What is the difference between a calorie and a Calorie?
A lowercase calorie (cal) is the amount of energy needed to raise 1 gram of water by 1°C — about 4.184 joules. A dietary Calorie (Cal, with a capital C) is actually a kilocalorie (kcal) — 1,000 small calories or 4,184 joules. When food labels say "200 Calories," they mean 200 kcal.
How many kWh is 1 litre of petrol?
One litre of petrol contains approximately 8.9 kWh of energy (about 32 MJ). This context helps compare electric vehicles (which use kWh directly) with petrol vehicles. A 50-litre petrol tank stores roughly 445 kWh of chemical energy, far more than most EV batteries (typically 50–100 kWh).
What is a BTU?
A British thermal unit (BTU) is the amount of energy needed to raise 1 pound of water by 1°F — about 1,055 joules. It is commonly used in the US for air conditioning capacity (BTU/hour) and heating systems. A 10,000 BTU/h air conditioner removes about 2.93 kW of heat.
