Energy Converter | Convert Joules, Calories, kWh, BTU, Electronvolts
Free online energy converter. Convert between joules, calories, kilowatt-hours, BTUs, electronvolts, and more. Accurate energy measurement conversion tool.
Free Online Energy Converter
Our energy converter tool allows you to instantly convert between different units of energy measurement. Whether you need to convert calories to joules for nutritional calculations, kilowatt-hours to joules for electricity bills, or electronvolts for physics calculations, our tool provides accurate results in real-time.
Supported Energy Units
SI Units
- Joule (J) SI base unit
- Kilojoule (kJ) 1000 joules
- Megajoule (MJ) 1 million joules
Common Units
- Calorie (cal) 4.184 joules
- Kilocalorie (kcal) 4184 joules
- BTU 1055.06 joules
Electrical Units
- Watt-hour (Wh) 3600 joules
- Kilowatt-hour (kWh) 3.6 million joules
Specialized Units
- Electronvolt (eV) 1.602e-19 joules
- Therm (thm) 105.5 million joules
- Foot-pound (ft·lb) 1.35582 joules
How to Use the Energy Converter
- Enter the value - Type the number you want to convert in the "Convert From" field
- Select "From" unit - Choose the unit you're converting from (e.g., calories)
- Select "To" unit - Choose the unit you want to convert to (e.g., joules)
- Get instant results - The converted value appears automatically
- Use quick values - Click on common values like "1 calorie" or "1 kWh" for quick conversion
Common Energy Conversion Examples
| Conversion | Formula | Example |
|---|---|---|
| Calories to Joules | cal × 4.184 = joules | 100 cal = 418.4 joules |
| Joules to Calories | J ÷ 4.184 = calories | 1000 J = 239 cal |
| kWh to Joules | kWh × 3,600,000 = joules | 1 kWh = 3.6 million joules |
| BTU to Joules | BTU × 1055.06 = joules | 5 BTU = 5275.3 joules |
| Electronvolts to Joules | eV × 1.602e-19 = joules | 1 eV = 1.602e-19 joules |
Practical Applications
⚡ Electricity & Power
Convert between kilowatt-hours and joules for electricity billing, appliance energy consumption, and power calculations.
🍎 Nutrition & Health
Convert between calories and joules for food energy content, dietary planning, and exercise energy expenditure.
🔬 Physics & Chemistry
Convert between electronvolts and joules for atomic physics, particle physics, and chemical bond energies.
🏭 Engineering & HVAC
Convert between BTUs and joules for heating, ventilation, air conditioning calculations, and thermal engineering.
Energy Measurement Systems
SI System (International System of Units)
The joule is the standard unit of energy in the SI system. It's defined as the amount of work done when a force of one newton displaces an object by one meter in the direction of the force.
- Used worldwide in scientific contexts
- Named after physicist James Prescott Joule
- Base unit for all energy calculations in physics
- 1 joule = 1 newton-meter = 1 watt-second
Nutritional Energy Units
The calorie (specifically the kilocalorie or Calorie with capital C) is commonly used in nutrition to measure food energy. 1 kilocalorie (food calorie) equals 4184 joules.
- Used worldwide for food labeling
- 1 Calorie (food calorie) = 1000 calories (thermochemical)
- Essential for diet planning and nutrition science
- Based on heat required to raise water temperature
Electrical Energy Units
The kilowatt-hour is the standard unit for electrical energy billing. It represents the energy consumed by a 1000-watt device operating for one hour.
- Used worldwide for electricity billing
- 1 kWh = 3.6 million joules
- Practical unit for large-scale energy consumption
- Standard for appliance energy ratings
💡 Conversion Tips
- Quick calorie to joule: Multiply calories by 4.2 (approx.)
- Quick joule to calorie: Divide joules by 4.2 (approx.)
- Quick kWh to MJ: Multiply kWh by 3.6
- Quick BTU to kJ: Multiply BTU by 1.055
- Remember: 1 food Calorie = 1 kilocalorie = 4184 joules
- For precise calculations, always use our converter tool
Start Converting Now!
Try our energy converter with these common conversions: