Energy Converter
Convert between energy units instantly: joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, and electronvolts. Free, 100% in your browser.
Reference
How does energy conversion work?
Energy conversion uses fixed ratios between units. This tool converts through joules (J) as the SI base unit. 1 calorie = 4.184 J (thermochemical), 1 kilocalorie (food Calorie) = 4,184 J, 1 watt-hour = 3,600 J, 1 BTU = 1,055.06 J, 1 electronvolt = 1.602×10⁻¹⁹ J. The joule is defined as the energy transferred when a force of one newton moves an object one meter.
Unit reference
SI: joule (J), kilojoule (kJ) — the standard scientific unit of energy. Thermal: calorie (cal) and kilocalorie (kcal/Cal) — used in food labeling and chemistry. Electrical: watt-hour (Wh), kilowatt-hour (kWh) — used for electricity billing and battery capacity. Imperial: British Thermal Unit (BTU) — used in HVAC and heating. Atomic: electronvolt (eV) — used in particle physics and quantum mechanics.
Common use cases
Nutrition — convert between kilocalories and kilojoules for food labeling. Electricity — understand energy bills by converting kWh to other units. HVAC — convert BTU ratings for heating and cooling systems. Physics — convert between SI energy units for calculations. Engineering — compare energy sources using consistent units.
Privacy
All calculations run 100% in your browser. No data is sent to any server.