Energy Converter

Welcome to the Energy Converter, the most comprehensive and user-friendly tool for converting between energy units. Whether you are a physicist calculating particle energies, an engineer designing HVAC systems, a nutritionist tracking caloric intake, or a homeowner understanding electricity bills, this converter provides instant, accurate conversions across 12 different energy units.

Supported Energy Units

This converter supports the most commonly used energy units across science, engineering, and everyday life:

Understanding Energy Units

The Joule - SI Unit of Energy

The Joule (J) is the standard SI unit of energy, named after physicist James Prescott Joule. One Joule equals:

• The work done when a force of 1 newton moves an object 1 meter
• The energy dissipated as heat when 1 ampere flows through 1 ohm for 1 second
• One watt of power for one second (1 W·s)

Calories vs Kilocalories

This is one of the most confusing aspects of energy units:

• Small calorie (cal): The energy to raise 1 gram of water by 1°C. Used in chemistry and physics.
• Large Calorie or kilocalorie (kcal): Equal to 1000 small calories. This is the "food calorie" on nutrition labels.

When food labels say "100 Calories," they actually mean 100 kilocalories (kcal) or 418,400 Joules.

BTU - British Thermal Unit

The BTU measures heat energy and is widely used in the United States for heating, ventilation, and air conditioning (HVAC) systems. One BTU is the energy needed to raise 1 pound of water by 1°F.

Kilowatt-hour - Electricity Unit

The kilowatt-hour (kWh) is the standard unit for measuring electricity consumption. It represents using 1000 watts of power for one hour.

Electronvolt - Particle Physics Unit

The electronvolt (eV) is the energy gained by an electron accelerating through 1 volt. Though tiny in everyday terms, it is the natural unit for atomic and particle physics.

Real-World Applications

How to Use This Converter

1. Select source unit: Click on the energy unit you want to convert from in the grid.
2. Enter value: Type your number in the input field. Decimals and large numbers are supported.
3. View results: All conversions appear instantly in the results grid below.
4. Toggle scientific notation: For very large or small numbers, enable scientific notation for cleaner display.
5. Copy results: Click the copy button on any result, or "Copy All" to get all conversions.

Conversion Formulas

All conversions use the Joule as the base unit. To convert from unit A to unit B:

Where Factor is the number of Joules per unit. For example, to convert 100 kcal to BTU:

Frequently Asked Questions

What is a Joule?

The Joule (J) is the SI unit of energy. It equals the work done when a force of one newton moves an object one meter. One Joule also equals one watt-second of electrical energy. Named after physicist James Prescott Joule, it is used universally in physics and engineering.

What is the difference between a calorie and a Calorie?

A lowercase calorie (cal) is the "small calorie" - the energy needed to raise 1 gram of water by 1°C. An uppercase Calorie (Cal) or kilocalorie (kcal) is the "food calorie" - equal to 1000 small calories. Food nutrition labels use kilocalories (kcal), often written as "Calories" with capital C.

How do I convert BTU to Joules?

To convert BTU to Joules, multiply by 1055.06. One BTU (British Thermal Unit) equals approximately 1055.06 Joules. BTU measures the heat needed to raise 1 pound of water by 1°F and is commonly used for heating/cooling systems in the US.

What is a kilowatt-hour (kWh)?

A kilowatt-hour (kWh) is a unit of energy equal to using 1000 watts for one hour, or 3,600,000 Joules. It is the standard billing unit for electricity consumption. For example, a 100W light bulb running for 10 hours uses 1 kWh of electricity.

What is an electronvolt (eV)?

An electronvolt (eV) is the energy gained by an electron when accelerated through a potential difference of 1 volt. Equal to approximately 1.602 × 10⁻¹⁹ Joules, it is commonly used in atomic, nuclear, and particle physics where Joules would be inconveniently small.

How many calories are burned running a mile?

Running one mile burns approximately 80-100 kilocalories (food calories) for an average person, which equals about 335,000-420,000 Joules of energy. The exact amount varies based on body weight, running speed, and individual metabolism.

Additional Resources

• Joule (Wikipedia)
• Calorie (Wikipedia)
• BTU (Wikipedia)
• Kilowatt-hour (Wikipedia)
• Electronvolt (Wikipedia)