Energy Converter

What this tool does

Energy Converter moves between the energy units used in nutrition, electricity bills, heating, physics and engineering. Each unit is defined against the joule with the official constant, including the exact electronvolt from the 2019 SI redefinition.

Energy is the same physical quantity whether it is in your breakfast, your electricity meter or a gas boiler, but each field counts it differently. Food packs list kcal and kJ, power companies bill in kilowatt-hours, heating engineers use BTU and therms, and physicists use electronvolts. Comparing them needs a common reference.

This converter uses the joule as its base. The thermochemical calorie is 4.184 J, so the food Calorie (kilocalorie) is 4,184 J. A watt-hour is 3,600 J and a kilowatt-hour 3.6 MJ. The British thermal unit uses the International Table value of 1,055.05585262 J, the therm is 100,000 BTU, and the electronvolt is exactly 1.602176634 × 10⁻¹⁹ J. Because everything links to the joule, any pair of units converts consistently, and nothing is sent to a server.

How to use Energy Converter

1. Enter the amount of energy in the Value field.
2. Select the starting unit in From, such as Kilowatt-hour (unit).
3. Select the target in To, such as Megajoule, and read the Result.
4. Use the swap button or change Decimal places if needed.
5. Review the full table to see the value in every energy unit.
6. Paste several values into Batch convert, for example monthly meter readings, and export a CSV.

Tips for better results

• To compare food energy, 1 kcal is 4.184 kJ; a 2,000 kcal diet is about 8,368 kJ per day.
• A kilowatt-hour is the energy a 1,000 W appliance uses in one hour.
• Very small values such as electronvolts switch to scientific notation automatically.

Common use cases

• Converting nutrition labels between kcal and kJ.
• Comparing electricity (kWh) and gas (therms or kWh) heating costs.
• Converting physics problem values between joules and electronvolts.
• Rating air-conditioner or heater capacities given in BTU.

Common mistakes to avoid

• Mixing up power (watts) and energy (watt-hours); use the Power Converter for rates.
• Reading "Calories" on a food label as small calories; they are kilocalories.
• Using an outdated or different BTU definition when a contract specifies one; this tool uses the International Table BTU.