CodesBeautify

Energy Converter

Convert energy across nineteen units, from electronvolts up to megawatt hours and tonnes of TNT.

Values
Converted
Runs locally in your browser

About the Energy Converter

Energy has more competing units than almost any other quantity, because chemistry, nutrition, electricity supply, heating engineering and particle physics each grew their own. The joule ties them together as the SI unit, and every factor here is expressed against it, so a nutrition label in kilojoules and a boiler rating in BTU can be compared directly.

Nutrition is the classic source of confusion. The Calorie printed on food packaging with a capital C is a kilocalorie, or 4184 joules, so a 250 Calorie snack holds 1046 kilojoules. Utility bills use the kilowatt hour, which is simply a kilowatt sustained for an hour and therefore 3.6 million joules. Heating and cooling equipment is rated in British thermal units, where one BTU is 1055.05585262 joules under the international table definition, and a US therm is one hundred thousand of those.

At the other extreme sit the electronvolt and its multiples, used whenever a single particle is the subject. A visible photon carries roughly 2 eV and a hydrogen atom needs 13.6 eV to ionise. The tonne of TNT is included because news reports describe explosions and asteroid impacts with it. Energy delivered over time is power, which the Power Converter handles.

How to use

  1. Paste the energy values you want to convert, one per line.
  2. Pick the source unit, such as joule or kilocalorie.
  3. Pick the target unit, such as kilowatt hour or BTU.
  4. Read the converted list, the exact factor and the table below it.

Common questions

How many joules are in a food Calorie?
A food Calorie is a kilocalorie, which is 4184 joules exactly under the thermochemical definition used here.
How many joules is one kWh?
3600000 joules, because a kilowatt for 3600 seconds delivers that much energy.
Which BTU definition does this use?
The international table BTU of 1055.05585262 joules, the figure quoted on most HVAC equipment.
Why is the electronvolt so small?
It is the energy one electron gains across a one volt difference, a scale suited to single particles rather than everyday objects.