Energy Converter

A kilocalorie (kcal) equals 1000 calories (cal). The 'Calories' listed on food packaging in the US and UK are actually kilocalories. So a 300 Calorie snack contains 300 kcal or 300,000 small calories. This distinction matters when converting nutrition data to joules or other units.

To convert calories to joules, multiply by 4.184. For example, 100 calories equals 418.4 joules. If converting food Calories (kcal) to joules, multiply by 4184 instead. The joule is the SI unit of energy used in physics and engineering.

There are 3,600,000 joules (3.6 MJ) in one kilowatt-hour. A kilowatt-hour is the unit used on electricity bills - running a 1000W device for 1 hour uses 1 kWh. This equals about 860 kcal or the energy in a typical meal.

A BTU (British Thermal Unit) is approximately 1055 joules and is the energy needed to raise 1 pound of water by 1°F. BTU is used in the US for rating air conditioners, furnaces and water heaters. A 10,000 BTU air conditioner uses about 2.93 kWh per hour.

To convert kilocalories to kilowatt-hours, divide by 860.421. For example, a 2000 kcal daily diet equals approximately 2.326 kWh of energy. This comparison helps illustrate that the human body runs on roughly the same energy as leaving a 100W light bulb on for 23 hours.