Energy Converter
Convert energy between joules, kilocalories, kilowatt-hours, BTUs, and more.
Energy Unit Reference
| Unit | Joules | kcal | Wh |
|---|---|---|---|
| 1 Joule | 1 | 0.000239 | 0.000278 |
| 1 kilojoule | 1,000 | 0.239 | 0.278 |
| 1 calorie | 4.184 | 0.001 | 0.00116 |
| 1 kilocalorie | 4,184 | 1 | 1.162 |
| 1 watt-hour | 3,600 | 0.860 | 1 |
| 1 kilowatt-hour | 3,600,000 | 860 | 1,000 |
| 1 BTU | 1,055 | 0.252 | 0.293 |
Frequently Asked Questions
What is the difference between a calorie and a kilocalorie?
A calorie (cal) is the amount of energy needed to raise 1 gram of water by 1°C. A kilocalorie (kcal) is 1,000 calories. The 'Calories' listed on food labels are actually kilocalories — so a 250 Calorie snack contains 250 kcal = 250,000 cal = 1,046,000 joules.
How many joules are in a kilowatt-hour?
One kilowatt-hour (kWh) equals 3,600,000 joules (3.6 MJ). This is because 1 kW = 1,000 J/s, and 1 hour = 3,600 seconds, so 1 kWh = 1,000 × 3,600 = 3,600,000 J.
What is a BTU?
A British Thermal Unit (BTU) is the amount of energy needed to raise 1 pound of water by 1°F. It equals approximately 1,055 joules or 0.293 watt-hours. BTUs are commonly used in the US for air conditioning, heating, and natural gas.
How much energy does a typical household use per day?
The average US household uses about 30 kWh per day (about 900 kWh/month). This equals roughly 108 MJ or 102,600 BTUs per day. Energy-efficient homes can cut this by 30–50%.
What is a foot-pound of energy?
A foot-pound (ft·lb) is the amount of energy needed to exert a force of 1 pound over a distance of 1 foot. It is equal to approximately 1.356 joules. In the US, it is commonly used to express torque in engine specifications.