Energy Converter

Convert between joules, calories, kilowatt-hours, BTU, and more.

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Background

Energy conversion connects nutrition, electricity, thermodynamics, and physics. Joules (SI), calories (nutrition), kWh (electricity), BTU (HVAC), and eV (physics).

Calories vs Kilojoules

1 kcal (Calorie) = 4.184 kJ. Australia uses kJ on labels; US uses Calories. 2,000 Cal diet = 8,368 kJ.

Electricity: kWh and Joules

1 kWh = 3,600,000 J. Australian household uses 15–20 kWh/day (~54–72 MJ).

How to Use This Calculator

Select 'Energy'
Choose the category from the dropdown.
Select your source unit
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Enter the value
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Select your target unit
Choose the unit you need.

Applications

Nutrition and Dietetics

500 Calories = 2,092 kJ. Understanding both helps read international nutrition labels.

Electricity and Solar

5 kW solar system produces ~20 kWh/day. Convert to compare across energy sources.

HVAC

12,000 BTU/hr air conditioner ≈ 3.5 kW. Common for room-size units.

Frequently Asked Questions

How do you convert Calories to kJ?

Multiply by 4.184. 500 Cal = 2,092 kJ. Food 'Calories' are kilocalories.

How do you convert kWh to joules?

1 kWh = 3,600,000 J = 3.6 MJ.

What is a BTU?

British Thermal Unit: energy to heat 1 lb water by 1°F. 1 BTU = 1,055 J.