Energy Converter

Verified formula Updated Jun 2026 Private — runs on your device

Verified formula Private

Kilojoule (kJ)

4.1840

Kilocalorie (kcal): 1.0000
Kilowatt-hour (kWh): 0.001162
BTU: 3.9657

For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.

How to use the Energy Converter

The Energy Converter works out your kilojoule (kj), along with 3 related figures in an instant. Enter energy and from unit and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.

Enter the energy.
Choose the from unit.
Read off your kilojoule (kj), together with kilocalorie (kcal), kilowatt-hour (kwh) and btu — the calculator updates automatically, with no button to press.

Worked example

For example, with energy of 1 and from unit of Kilocalorie (kcal), the kilojoule (kj) is 4.1840.

Inputs used
Energy	1
From unit	Kilocalorie (kcal)

Results
Kilojoule (kJ)	4.1840
Kilocalorie (kcal)	1.0000
Kilowatt-hour (kWh)	0.001162
BTU	3.9657

Results are estimates for educational use, not professional advice.

Frequently asked questions

One kilocalorie (the food Calorie) equals 4.184 kilojoules. So a 100 kcal snack is about 418 kJ.

A small calorie is the energy to heat 1 g of water by 1°C. The food Calorie on labels is a kilocalorie, which is 1000 small calories.

One kilowatt-hour is 3,600,000 joules, the energy of using 1000 watts for one hour.

A British Thermal Unit is about 1055 joules, often used to rate heating and air-conditioning equipment.

Enter the energy. Choose the from unit. Read off your kilojoule (kj), together with kilocalorie (kcal), kilowatt-hour (kwh) and btu — the calculator updates automatically, with no button to press.