Energy Converter

Convert between joules, kilojoules, calories, kilowatt-hours, electronvolts, and more.

Energy Conversion

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Common Energy Conversions

J to kJ
kJ to J
cal to J
J to cal
kWh to J
J to kWh

kcal to kJ
kJ to kcal
eV to J
J to eV
BTU to J
J to BTU

Energy is a fundamental quantity in physics, representing the capacity to do work. It exists in many forms, including kinetic, potential, thermal, electrical, chemical, and nuclear energy, and can be converted from one form to another.

The SI unit of energy is the joule (J), named after James Prescott Joule. Other common units include the kilojoule (kJ), calorie (cal), kilowatt-hour (kWh), electronvolt (eV), and British thermal unit (BTU). Each unit is used in different contexts, from nutrition (calories) to electricity billing (kWh) to particle physics (eV).