Popup calculator Copy a link to this page Print this page Email a link to this page Scroll up to form What does this mean? Remove this row Open/Close content Close content Return to content Copy to clipboard

Energy Converter

Spelling: American | British
Use this energy converter to convert instantly between calories, joules, kilocalories, kilowatt-hours and other metric and imperial energy units.

Disclaimer: Whilst every effort has been made in building our calculator tools, we are not to be held liable for any damages or monetary losses arising out of or in connection with their use. Full disclaimer.

Energy comes in various forms and units of energy span both metric and imperial systems, making it useful to have a reliable energy conversion tool.

How to use the converter

To use our energy converter, simply select the energy unit you want to convert from and to and enter a figure into the 'value' box. The calculator will then return the conversion value for you.

Let's take a look at some of the more common units of energy available and review some tips on how to reduce your energy use.

Common units of energy

  • Joule (J): The joule is the standard unit of energy in the International System of Units (SI). It is defined as the energy transferred when a force of one newton acts on an object over a distance of one meter.
  • Calorie (cal): The calorie is a unit of energy used in nutrition. One calorie is the amount of energy required to raise the temperature of one gram of water by one degree Celsius.
  • Kilowatt-Hour (kWh): Kilowatt-hours are commonly used to measure electricity consumption. One kilowatt-hour is equivalent to one kilowatt of power used for one hour. To see how this applies to electric vehicles and compare their efficiency, take a look at our MPGe Calculator, which translates kilowatt-hours into easily understandable metrics like MPGe, helping you gauge an EV's energy consumption.
  • Electronvolt (eV): Electronvolts are often used in particle physics and quantum mechanics. One electronvolt is equal to the amount of kinetic energy gained or lost by an electron when accelerated through an electric potential difference of one volt.

Note that we have a separate Newton-meters to foot-pounds converter available. And, should you wish to convert between kilojoules and calories for food energy, you can use our kj to calories converter.

Energy conservation tips

Converting between energy units is not just about calculations; it's also about making informed choices to conserve energy. Here are some tips to help you save energy and reduce your environmental footprint:

  • Switch to energy-efficient appliances.
  • Seal gaps and insulate your home to reduce heating and cooling energy consumption.
  • Use public transportation or carpool to reduce fuel consumption.
  • Turn off lights and unplug devices when not in use.
  • Opt for renewable energy sources like solar or wind power.

The EnergySage website offers 16 practical tips for improving energy efficiency at home. Key suggestions include improving insulation, replacing traditional light bulbs with Energy Star-certified LED bulbs, using smart power strips to eliminate "phantom energy," and installing programmable or smart thermostats for better control of heating and cooling. Other tips include washing clothes in cold water, using smaller cooking appliances, and adjusting daily behaviors to save energy.

You can use our electricity calculator to work out how much your appliances are costing you to use, to aid your energy efficiency decision making.

Conversion units for the Energy Converter

British Thermal Units (Btu), Calories (kcal), Calories (th) (cal (th)), Electron Volt (eV), Ergs, Foot Pounds (ft*lbf), Gigajoules (GJ), Joules (J), Kilocalories (th) (kcal), Kilojoules (kJ), Kilowatt-Hour (kW*h), Megajoules (MJ), Millijoules (mJ),


To help with productivity, we now set a cookie to store the last units you have converted from and to. This means that when you re-visit this energy converter, the units will automatically be selected for you.