Energy Converter
Convert between any energy units instantly. Our free energy converter handles joules, calories, kilowatt-hours, BTU, electron volts, and more. Real-time conversions with high precision for science, engineering, and nutrition.
Enter a value to see conversions
Quick Reference
All conversions happen in your browser. No data is sent to any server.
Embed This Tool
Add this tool to your website with customizable styling
How to Use
- 1 Enter an energy value in the input field at the top of the converter.
- 2 Select your input unit from the dropdown menu (joules, calories, kWh, BTU, etc.).
- 3 Choose your target unit from the second dropdown to see the converted value instantly.
- 4 View all conversions in the reference table below showing your energy value in all supported units.
- 5 Use reference points - Click on common energy values (like boiling water or powering a light bulb) to see instant conversions.
Pro Tip: Use the reference points to quickly understand everyday energy amounts — like the energy in food, batteries, or household appliances. Perfect for science students and engineers!
Frequently Asked Questions
What's the difference between calories and kilocalories?
A kilocalorie (kcal) equals 1,000 calories. Food labels use 'Calories' (capital C) which actually means kilocalories. 1 food Calorie = 1 kcal = 4,184 joules.
When should I use joules vs kilowatt-hours?
Joules (J) are the SI unit for energy, used in physics and engineering. Kilowatt-hours (kWh) are used for electrical energy billing. 1 kWh = 3.6 million joules.
What are BTUs used for?
BTU (British Thermal Unit) is commonly used in HVAC, heating, and cooling systems. It represents the energy needed to heat one pound of water by one degree Fahrenheit. 1 BTU ≈ 1,055 joules.
What is an electron volt?
An electron volt (eV) is a tiny unit of energy used in atomic and particle physics. It's the energy gained by an electron moving through a potential difference of one volt. 1 eV = 1.602 × 10⁻¹⁹ joules.