Convert Energy
Convert energy measurements between different units quickly and accurately
Energy Conversion Calculator
Popular Energy Conversions
Quickly convert between the most commonly used energy units.
Understanding Energy Measurements
Energy conversions are essential for various applications, from electrical engineering and physics to everyday energy consumption and environmental science. Understanding energy conversions ensures accurate and consistent results across different measurement systems.
Common Energy Units
Metric Units
- Joule (J) - SI base unit
- Kilojoule (kJ) - 1,000 joules
- Megajoule (MJ) - 1,000,000 joules
- Gigajoule (GJ) - 1,000,000,000 joules
Electrical Units
- Watt-hour (Wh) - Small devices
- Kilowatt-hour (kWh) - Household consumption
- Megawatt-hour (MWh) - Industrial consumption
- Gigawatt-hour (GWh) - National grid scale
Thermal Units
- Calorie (cal) - Small food energy
- Kilocalorie (kcal) - Food energy
- British Thermal Unit (BTU) - HVAC systems
- Therm (thm) - Natural gas energy
Mechanical Units
- Foot-pound (ft⋅lb) - Mechanical work
- Inch-pound (in⋅lb) - Small mechanical work
- Kilogram-force meter (kgf⋅m) - Engineering
Common Applications
| Field | Measurement Types | Typical Uses |
|---|---|---|
| Electrical Engineering | Joules, Watt-hours | Power consumption, energy efficiency |
| Physics | Joules, Calories | Energy transfer, heat calculations |
| Nutrition | Calories, Kilocalories | Food energy, dietary planning |
| Environmental Science | Joules, Kilowatt-hours | Energy conservation, sustainability |
| HVAC Systems | BTU, Joules | Heating and cooling calculations |
| Atomic Physics | eV, keV, MeV | Particle energy, nuclear reactions |
Conversion Tips
- Use a calculator for precise energy conversions
- For quick estimates: 1 calorie = 4.184 joules
- Remember that 1 kilowatt-hour = 3.6 megajoules
- For electrical energy, use watt-hours or kilowatt-hours
- For thermal energy, use joules or calories
- For food energy, use kilocalories (often called 'calories')
- For atomic physics, use electron volts (eV, keV, MeV)
Energy Conversions
| Conversion | Formula/Rule | Quick Answer |
|---|---|---|
| Joules to Calories | 1 cal = 4.184 J | Divide J by 4.184 |
| Calories to Joules | 1 J = 0.239 cal | Multiply cal by 4.184 |
| Joules to Kilowatt-hours | 1 kWh = 3.6 MJ | Divide J by 3,600,000 |
| Kilowatt-hours to Joules | 1 J = 0.0000002778 kWh | Multiply kWh by 3,600,000 |
| Kilojoules to Calories | 1 cal = 4.184 J | Divide kJ by 4.184 |
| Calories to Kilojoules | 1 kJ = 0.239 cal | Multiply cal by 4.184 |
| Megajoules to Kilowatt-hours | 1 kWh = 3.6 MJ | Divide MJ by 3.6 |
| Kilowatt-hours to Megajoules | 1 MJ = 0.2778 kWh | Multiply kWh by 3.6 |
| BTU to Joules | 1 BTU = 1055.06 J | Multiply BTU by 1055.06 |
| Joules to BTU | 1 J = 0.000948 BTU | Divide J by 1055.06 |
| Foot-pounds to Joules | 1 ft⋅lb = 1.356 J | Multiply ft⋅lb by 1.356 |
| Joules to Foot-pounds | 1 J = 0.738 ft⋅lb | Divide J by 1.356 |
Our energy conversion tool provides accurate conversions between all major energy units, making it easy to switch between different systems. Whether you're working in electrical engineering, physics, or environmental science, our converter ensures precise energy conversions for any application.
Energy Conversion Questions
Everything you need to know about energy measurements and conversions
What's the difference between energy and power?
Energy is the amount of work that can be done, measured in joules or kilowatt-hours. Power is the rate at which energy is used or transferred, measured in watts. Think of energy as the total amount of fuel in a tank, and power as how fast you're using that fuel. 1 kilowatt of power used for 1 hour equals 1 kilowatt-hour of energy.
How do I convert between calories and joules?
1 calorie (cal) = 4.184 joules (J). To convert calories to joules, multiply by 4.184. To convert joules to calories, divide by 4.184. Note that food 'calories' are actually kilocalories (kcal), so 1 food calorie = 4,184 joules. This is why a 100-calorie snack contains 418,400 joules of energy.
What is the relationship between kWh and joules?
1 kilowatt-hour (kWh) = 3,600,000 joules (3.6 MJ). This comes from: 1 kW = 1,000 watts, 1 hour = 3,600 seconds, so 1 kWh = 1,000 × 3,600 = 3,600,000 joule-seconds = 3.6 megajoules. Your electric bill measures energy in kWh because it's more practical than using millions of joules.
How do BTUs relate to other energy units?
1 BTU (British Thermal Unit) = 1,055.06 joules ≈ 0.293 watt-hours. BTUs are commonly used in HVAC systems. For reference: a typical home air conditioner might be rated at 12,000 BTU/hour (3.5 kW), and a gallon of gasoline contains about 114,000 BTU (33.4 kWh) of energy.
What are electron volts (eV) used for?
Electron volts measure very small amounts of energy at the atomic and subatomic level. 1 eV = 1.602 × 10⁻¹⁹ joules. Common units are keV (1,000 eV), MeV (1,000,000 eV), and GeV (1,000,000,000 eV). X-rays have energies of 1-100 keV, while particle accelerators can produce beams with GeV energies.
How much energy does the average home use?
The average US home uses about 10,500 kWh per year (37.8 GJ), or roughly 29 kWh per day. This varies greatly by region, home size, and efficiency. For comparison, this is equivalent to about 9 billion calories, 36 million BTU, or enough energy to lift a car 2,400 miles straight up against gravity.
What's the difference between mechanical and thermal energy units?
Mechanical energy units like foot-pounds (ft⋅lb) measure work done by forces - like lifting weights or tightening bolts. Thermal energy units like calories and BTUs measure heat energy. While both can be converted to joules, they represent different types of energy transfer. 1 ft⋅lb = 1.356 J, while 1 cal = 4.184 J.
Have more questions? Contact us!