Energy Converter — Convert All Energy Units Online

Joule

The joule (J) is the SI unit of energy. It is defined as the work done by a force of one newton acting through a distance of one metre. Joules measure mechanical, electrical, and thermal energy.

1 J to kJ 1 J to MJ 1 J to cal 1 J to kcal 1 J to Wh 1 J to kWh 1 J to BTU

Kilojoule

The kilojoule (kJ) equals 1,000 joules. It is used in nutrition labelling in many countries and for measuring the energy content of foods, chemical reactions, and industrial processes.

1 kJ to J 1 kJ to MJ 1 kJ to cal 1 kJ to kcal 1 kJ to Wh 1 kJ to kWh 1 kJ to BTU

Megajoule

The megajoule (MJ) equals 1,000,000 joules. It is used for measuring the energy content of fuels, large-scale industrial energy consumption, and scientific experiments.

1 MJ to J 1 MJ to kJ 1 MJ to cal 1 MJ to kcal 1 MJ to Wh 1 MJ to kWh 1 MJ to BTU

Calorie

The calorie (cal) equals 4.184 joules. It was originally defined as the energy needed to raise one gram of water by one degree Celsius. Small calories are used in chemistry and physics.

1 cal to J 1 cal to kJ 1 cal to MJ 1 cal to kcal 1 cal to Wh 1 cal to kWh 1 cal to BTU

Kilocalorie

The kilocalorie (kcal), often called a food Calorie (with capital C), equals 1,000 calories or 4,184 joules. It is the standard unit for measuring the energy content of food and beverages in nutrition.

1 kcal to J 1 kcal to kJ 1 kcal to MJ 1 kcal to cal 1 kcal to Wh 1 kcal to kWh 1 kcal to BTU

Watt-hour

The watt-hour (Wh) equals 3,600 joules. It measures electrical energy consumption over time. Battery capacities for small devices are often measured in watt-hours.

1 Wh to J 1 Wh to kJ 1 Wh to MJ 1 Wh to cal 1 Wh to kcal 1 Wh to kWh 1 Wh to BTU

Kilowatt-hour

The kilowatt-hour (kWh) equals 3,600,000 joules. It is the standard unit on electricity bills and measures the energy consumed by households, businesses, and industrial facilities.

1 kWh to J 1 kWh to kJ 1 kWh to MJ 1 kWh to cal 1 kWh to kcal 1 kWh to Wh 1 kWh to BTU

British thermal unit

The British thermal unit (BTU) equals approximately 1,055 joules. It is used in the United States for rating heating and cooling systems, water heaters, and the energy content of fuels.

1 BTU to J 1 BTU to kJ 1 BTU to MJ 1 BTU to cal 1 BTU to kcal 1 BTU to Wh 1 BTU to kWh

What Is Energy?

Energy is the capacity to do work or transfer heat. It exists in many forms: kinetic, potential, thermal, electrical, chemical, and nuclear. Energy is conserved — it can be converted from one form to another but cannot be created or destroyed.

SI Energy Units

The joule (J) is the SI unit of energy, defined as the work done by a force of one newton acting through one metre. The kilojoule (kJ) and megajoule (MJ) are used for larger quantities. The calorie (cal) equals 4.184 joules and was originally defined as the energy needed to heat one gram of water by 1°C. The kilocalorie (kcal), often called a food Calorie, is used in nutrition labelling.

Electrical and Thermal Energy

The watt-hour (Wh) and kilowatt-hour (kWh) measure electrical energy consumption — your electricity bill is calculated in kWh. The British thermal unit (BTU) is used in heating, cooling, and HVAC systems, primarily in the United States.