⚡ Energy Converter
Convert between Joules, Kilojoules, Calories, Kilocalories, Watt-hours, kWh, BTU, Electronvolts, and Foot-pounds instantly.
Quick Reference
How to Convert Energy Units
Energy is the capacity to do work. This converter works by converting every input to the base unit (Joules), then to the target unit. Energy measurement is essential in physics, nutrition, electricity billing, and engineering.
Common Conversion Factors
| From | To | Multiply by |
|---|---|---|
| Kilowatt-hour | Joules | 3,600,000 |
| Kilocalorie | Joules | 4,184 |
| BTU | Joules | 1,055.06 |
| Calorie | Joules | 4.184 |
| Watt-hour | Joules | 3,600 |
| Foot-pound | Joules | 1.35582 |
| kWh | BTU | 3,412.14 |
Energy in Everyday Life
Food energy is measured in kilocalories (Calories). An average adult needs 2,000–2,500 kcal per day. Electricity is billed in kilowatt-hours — a typical US household uses about 900 kWh per month. Heating/cooling capacity is rated in BTU; a window AC unit might be rated at 8,000 BTU/hour.
Energy Quick Reference
| kWh | Joules | BTU | kcal |
|---|---|---|---|
| 0.001 | 3,600 | 3.41 | 0.860 |
| 1 | 3,600,000 | 3,412 | 860 |
| 10 | 36,000,000 | 34,121 | 8,598 |
| 100 | 360,000,000 | 341,214 | 85,985 |
| 1,000 | 3,600,000,000 | 3,412,142 | 859,845 |
Frequently Asked Questions
A lowercase calorie (cal) is the energy needed to raise 1 gram of water by 1°C. A food Calorie (Cal or kcal) equals 1,000 small calories. When nutrition labels say "200 Calories," they mean 200 kilocalories or 200,000 small calories.
A kilowatt-hour (kWh) is the energy consumed by a 1,000-watt appliance running for one hour. It equals 3,600,000 joules or about 3,412 BTU. Your electricity bill is measured in kWh — multiply appliance watts × hours of use ÷ 1,000 to find kWh consumed.
A British Thermal Unit (BTU) is the energy required to raise one pound of water by 1°F. It equals approximately 1,055.06 joules. BTUs are commonly used to rate heating systems, air conditioners, and fuel energy content in the US.
Multiply the appliance wattage by hours of use, divide by 1,000 to get kWh, then multiply by your electricity rate. For example: a 2,000W heater running 5 hours = 10 kWh. At $0.12/kWh, that costs $1.20 per session.