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Energy converter

Convert kWh, kilocalories, and BTU without mixing food Calories.

This tool processes files and text locally in your browser. Your content is not uploaded or stored by this site.

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What this tool does

The joule is the base. A kilowatt-hour is 3.6 MJ. A thermochemical calorie is 4.184 J. A food Calorie is a kilocalorie (4184 J). BTU uses the International Table value.

How to use it

  1. Enter the energy.
  2. Pick source and destination units.
  3. Convert and copy the JSON.

Supported input

  • A number and two energy units from the menu

Output

  • JSON with the converted energy plus every other unit in the family

Privacy

This tool processes files and text locally in your browser. Your content is not uploaded or stored by this site.

ConvertPass does not include your input in analytics, URLs, or error reports. Encoding: Decimal numbers / SI joule. Limit: A single energy (4.0 KB).

Limitations

  • Nutrition labels round. This is not a dietitian and not an electricity bill.
  • Electronvolts, therms, and ton-of-TNT are not in the menu.
  • A ‘large calorie’ vs ‘small calorie’ mix-up is why kcal is labelled as food Calorie.

Example

Input
1 kWh → kJ
Output
{
  "result": 3600,
  "formatted": "1 kWh = 3600 kJ"
}

Troubleshooting

A food label in kJ does not match kcal × 4.184
Labels often use 4.2 or round to the nearest 10 kJ. This page uses 4.184 J per calorie exactly.

FAQ

Is a Calorie the same as a calorie?

On food packaging, Calorie usually means kilocalorie. Pick kcal, not cal.

How many joules in a kilowatt-hour?

3,600,000. That is an hour at one kilowatt.

Which BTU is this?

The International Table BTU, 1055.05585262 J. Not the thermochemical BTU.

Can I convert therms of gas?

No. A therm is a gas-industry unit ConvertPass does not list.

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Last reviewed 16 August 2026. Report a problem. Reports do not include your input.