📌 Overview

Convert energy units including joule, kilojoule, calorie, kilocalorie, watt-hour, kilowatt-hour, BTU and electronvolt.

⚡ Energy Converter

Convert energy units including joule, kilojoule, calorie, kilocalorie, watt-hour, kilowatt-hour, BTU and electronvolt.

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📋 How to Use

Enter the energy value.
Choose source and target units.
Read the converted result instantly.
Check the full list below for all units at once.

❓ FAQ

Is a food calorie the same as a calorie?

No. The "calorie" on nutrition labels is actually a kilocalorie (kcal) — 1000 small calories. A 500 kcal meal is 500,000 calories in physics terms.

How many joules in 1 kWh?

1 kilowatt-hour = 3,600,000 joules (3.6 MJ). That is one kilowatt sustained for one hour.

❓ More Questions

Is the calorie on food labels the same as the physics calorie?

No. The calorie on nutrition labels is actually a kilocalorie (kcal), equal to 1000 small calories. A 500-calorie meal is 500,000 small calories in physics units.

How many joules in 1 kWh of electricity?

1 kilowatt-hour (1 degree of electricity) = 3,600,000 joules = 3.6 megajoules, i.e. the energy of 1 kilowatt running for 1 hour.

💡 Use Cases

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Nutrition

Convert kJ on labels to kcal.

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Electricity

Relate kWh on your bill to joules.

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HVAC

Work with BTU ratings.

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📖 Deep Dive: Energy Converter

The international unit of energy

The joule (J) is the international standard unit of energy, defined as the work done by one newton of force acting over one meter. Every other energy unit can be converted into joules.

Common units by field

Food nutrition: kilocalorie (kcal) and kilojoule (kJ), 1 kcal = 4.184 kJ.

Electricity: kilowatt-hour (kWh), 1 kWh = 3.6 MJ.

HVAC: British thermal unit (BTU), 1 BTU is about 1055 J.

Microphysics: electronvolt (eV), 1 eV is about 1.602 times 10 to the power of -19 J.

A practical conversion

A food labeled 1500 kJ per 100g converts to kcal: 1500 divided by 4.184 is about 358 kcal. Chinese nutrition labels usually show kilojoules directly, so people used to kcal need to divide by 4.184.

What air-conditioner BTU means

An air conditioner rated 12000 BTU/h is about 3.5 kW, commonly called a 1.5-horsepower unit. BTU is energy per hour, so keep energy and power distinct when converting.