Energy Converter

The Energy Converter allows you to convert between seven widely used energy units: joules, calories, kilocalories, kilowatt-hours, British Thermal Units, electron volts, and foot-pounds. Energy is one of the most fundamental quantities in physics, engineering, nutrition, and everyday life, and different fields use different units to measure it.

The joule is the SI standard unit of energy, used in physics and engineering. Calories and kilocalories are common in chemistry and nutrition, where food energy is typically measured in kilocalories (often labeled simply as Calories with a capital C on food packaging). Kilowatt-hours are the standard unit for electrical energy billing. BTU is widely used in the heating, ventilation, and air conditioning (HVAC) industry in the United States. Electron volts are the preferred unit in particle physics and quantum mechanics. Foot-pounds are used in mechanical engineering, particularly for torque and work calculations.

The converter uses joules as the internal base unit. Every input is first converted to joules, then converted from joules to the target unit. All conversion factors are based on internationally recognized standard definitions. For example, one calorie equals exactly 4.184 joules (thermochemical calorie), one kWh equals exactly 3,600,000 joules, and one BTU equals approximately 1,055.06 joules.

All calculations run entirely in your browser. No data is sent to any server, keeping your inputs private. Results are displayed with up to six decimal places, with trailing zeros removed for readability.