Energy converter
Type a value and pick the starting unit: joules, calories, kilocalories, watt-hours, kilowatt-hours and BTU convert in real time, with real-world examples to help you picture the amounts.
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Calories vs. kilocalories: what food labels really mean
The "calorie" you count at the dinner table is actually a kilocalorie: 1 kcal = 1,000 calories = 4,184 joules. That's why nutrition facts labels list Calories with a capital C — they mean kcal (European labels also add kJ, the official SI-based unit). For scale, a medium apple provides about 95 kcal, which is nearly 400,000 joules. The nutrition figures shown here are averages and for general information only: this tool provides estimates only and is not medical or dietary advice — consult a doctor or registered dietitian for specific needs.
The kWh: the unit on your electric bill
A kilowatt-hour is the energy used by a 1,000-watt appliance running for one hour, and it equals 3.6 million joules. It's what your utility company bills you for: a hot laundry cycle uses roughly 1 kWh, a 2,000 W hair dryer burns through one in half an hour, and a modern refrigerator uses about 0.5–0.8 kWh per day. If you prefer imperial units, 1 kWh is about 3,412 BTU — the unit used to rate furnaces and air conditioners in the US. Converting kWh into kcal, joules or BTU lets you compare electricity use and "food energy" on the same scale.