Energy Unit Converter
Full Reference Table
Enter a value above and click Convert to populate the table.
| Unit | Value |
|---|
Energy Unit Conversion Guide
Energy appears in many forms — heat, electricity, chemical, and mechanical — and each field uses its preferred unit. Our free energy converter supports eight major energy units, making it easy to switch between joules, calories, kilowatt-hours, BTU, and more with a full reference table.
Joule — The SI Unit of Energy
The joule (J) is the SI standard unit of energy, defined as the work done when a force of one newton moves an object one meter. It is the universal scientific currency for energy. One joule equals one watt-second (1 J = 1 W·s). All other energy units can be expressed in joules.
Calories and Kilocalories in Nutrition
In everyday nutrition, "Calories" (with a capital C) refers to kilocalories (kcal) — the energy needed to raise 1 kg of water by 1°C. A food label saying "200 Calories" means 200 kcal = 836,800 joules. The lowercase "calorie" (cal) is the thermochemical calorie equal to 4.184 J, used in chemistry labs. This distinction causes frequent confusion.
Kilowatt-Hours on Your Electricity Bill
The kilowatt-hour (kWh) is the unit on household electricity bills. One kWh is the energy used by a 1,000-watt appliance running for one hour, equal to 3,600,000 joules (3.6 MJ). An average household in the UK uses about 2,700–3,100 kWh per year. A 2 kW electric kettle used for 5 minutes consumes approximately 0.167 kWh.
BTU in Heating and Cooling
The British Thermal Unit (BTU) is the amount of heat needed to raise one pound of water by 1°F. It is widely used in the US and UK for air conditioning, heating systems, and boilers. One BTU equals approximately 1,055 joules. A typical home air conditioner is rated at 5,000–12,000 BTU/hour.
Electronvolts in Particle Physics
The electronvolt (eV) is the energy gained by an electron moving through a 1-volt potential difference. It is tiny — 1 eV = 1.602 × 10⁻¹⁹ joules — but it is the natural unit for atomic, nuclear, and particle physics. Proton beam energies at particle accelerators reach GeV (giga-electronvolts) or TeV (tera-electronvolts).