Energy Converter
Convert joules, calories, kWh, BTU, and other energy units.
Unit
Energy Converter
Generated on April 24, 2026
?What is the Energy Converter?
An energy converter moves between units used in physics (joules, electron-volts), nutrition (calories, kilocalories), electricity (kilowatt-hours, BTUs), and engineering. All measure the same physical quantity — the capacity to do work — but at vastly different scales, from the 10⁻¹⁹ joules of one electron-volt to the 3.6 million joules of one kilowatt-hour. A particularly common source of confusion is the nutrition Calorie (capital C), which is really a kilocalorie (1,000 small calories) — a single food 'Calorie' on a label equals 4,184 joules.
The Formula
A joule is the energy transferred when 1 newton of force acts through 1 meter. The large differences between these units come from their origins: kilowatt-hours suit household electricity billing (1 kW applied for 1 hour = 3,600 kJ), BTUs fit US/UK heating and air-conditioning ratings (energy to heat 1 lb of water by 1 °F), and kcal fits human nutrition. Electron-volts are tiny because they measure individual particle interactions — 1 J equals 6.24 × 10¹⁸ eV.
Practical Examples
One food Calorie (as printed on nutrition labels) equals 4,184 joules — a single M&M candy contains about 4 Calories or 17 kJ.
1 kWh of electricity (a typical hour of air conditioning) equals 3.6 million joules — also equal to running ten 100 W bulbs for one hour.
A daily 2,000 kcal diet delivers 8.37 megajoules of energy — roughly what the average adult body burns in a day.
1 BTU ≈ 1,055 joules — air conditioners are often rated in BTU/hour, where 12,000 BTU/hr equals roughly 3.5 kW of cooling.
The kinetic energy of a 1,500 kg car at 60 km/h is about 208 kJ — equivalent to 50 kcal, or the energy in a single cookie.