Energy Converter

Convert between different energy units from mechanical, thermal, electrical, chemical, and nutritional domains.

SI Units
Joule (J)
Kilojoule (kJ)
Megajoule (MJ)
Millijoule (mJ)
Electrical Units
Watt-hour (Wh)
Kilowatt-hour (kWh)
Megawatt-hour (MWh)
Thermal Units
Calorie (cal)
Kilocalorie (kcal)
British Thermal Unit (BTU)
Imperial/US Units
Foot-pound (ft•lbf)
Inch-pound (in•lbf)
Horsepower-hour (hp•h)
Nutritional Units
Food Calorie (kcal)
Food Kilojoule (kJ)
Other Units
Electronvolt (eV)
Therm (US)
Therm (UK)
Ton of TNT
Conversion Result
100 J = 100 kJ
Conversion Formula

1 Joule (J) = 0.001 Kilojoule (kJ)

100 J × 0.001 = 0.1 kJ

About Energy Units

Energy is the capacity to do work. It exists in various forms including kinetic, potential, thermal, electrical, chemical, nuclear, and others. The SI unit of energy is the joule (J), named after English physicist James Prescott Joule.

Energy conversion is essential in physics, engineering, chemistry, biology, and everyday life. This tool helps convert between different energy units used across these disciplines.

  • Joules to Calories: 1 J = 0.239 cal
  • Calories to Joules: 1 cal = 4.184 J
  • kWh to Joules: 1 kWh = 3,600,000 J
  • BTU to Joules: 1 BTU = 1,055.06 J
  • eV to Joules: 1 eV = 1.60218 × 10⁻¹⁹ J

Joule: Named after James Prescott Joule who demonstrated that heat is a form of energy.

Calorie: From Latin "calor" meaning heat, originally defined as the heat needed to raise water temperature.

BTU: British Thermal Unit dates back to the early days of steam engine development.

Electronvolt: Developed in early 20th century for atomic and nuclear physics.