Energy Converter
Convert between different energy units
Energy Converter
Common Energy References
Daily Life
Food Calorie: 1 kcal
AA Battery: ~5 Wh
Car Battery: ~500 Wh
Daily Home Use: 30 kWh
Gallon of Gas: 33.7 kWh
Large Scale
Lightning Bolt: ~1-5 GJ
Ton of TNT: 4.184 GJ
Hurricane: ~600 TJ
Nuclear Bomb: ~84 TJ
Annual US Energy: ~100 EJ
Complete Energy Conversion Guide
Comprehensive guide to energy measurements, conversions, and real-world applications
Understanding Energy Measurement Systems
SI & Mechanical Energy Units
- •Joule (J): SI base unit (1 kg·m²/s²)
- •Kilojoule (kJ) = 1,000 J
- •Megajoule (MJ) = 1,000,000 J
- •Newton-meter (N·m) = 1 J
- •Erg = 10⁻⁷ J (CGS system)
- •Foot-pound (ft·lbf) = 1.35582 J
Thermal & Electrical Energy
- •Calorie (cal) = 4.184 J (raises 1 g water by 1°C)
- •Kilocalorie (kcal) = 4,184 J (food calorie = 1 kcal)
- •BTU = 1,055.06 J
- •Therm = 100,000 BTU
- •Watt-hour (Wh) = 3,600 J
- •Kilowatt-hour (kWh) = 3,600,000 J
- •Electron-volt (eV) = 1.602 × 10⁻¹⁹ J
Essential Conversion Factors
Mechanical Energy
- •1 kJ = 1,000 J
- •1 ft·lbf = 1.35582 J
- •1 BTU = 1,055.06 J
- •1 cal = 4.184 J
- •1 kcal = 4,184 J
- •1 erg = 10⁻⁷ J
Electrical Energy
- •1 Wh = 3,600 J
- •1 kWh = 3,600,000 J
- •1 MWh = 3.6 × 10⁹ J
- •1 kWh = 3,412.14 BTU
- •1 kWh = 859.845 kcal
- •1 therm = 29.307 kWh
Scientific Units
- •1 eV = 1.602 × 10⁻¹⁹ J
- •1 MeV = 1.602 × 10⁻¹³ J
- •1 GeV = 1.602 × 10⁻¹⁰ J
- •1 TNT ton = 4.184 × 10⁹ J
- •1 barrel of oil ≈ 6.117 × 10⁹ J
Professional Applications
Food & Nutrition
- •Caloric content labeling (kcal per serving)
- •Daily energy needs (2,000–2,500 kcal/day)
- •Macronutrient energy density (fat: 9 kcal/g; protein & carbs: 4 kcal/g)
- •Sports nutrition (glycogen storage ~1,700 kcal)
- •Metabolic rate calculations
Electrical Engineering
- •Utility billing (kWh)
- •Battery capacity (Wh or kWh)
- •Solar panel output (kWh/day)
- •EV range calculations
- •Data center PUE analysis
- •Grid-scale storage (MWh)
- •Household energy audits
HVAC & Building
- •Heating value of fuels (BTU/therm, BTU/gallon)
- •Heat pump COP
- •Building energy codes (kWh/m²·year)
- •District heating systems
- •Insulation R-values and heat loss (BTU/h)
Physics & Industry
- •Nuclear energy (MeV per fission)
- •Particle accelerators (GeV)
- •Chemical bond energies (kJ/mol)
- •Explosive yield (TNT equivalent)
- •Industrial furnaces (MJ per process)
- •Combustion engineering
Energy Measurement Best Practices
Unit Awareness
- •Food labels use kcal (not cal)
- •kWh is energy, not power
- •BTU is a quantity of heat, not a rate (BTU/h is rate)
- •Electron-volts are for quantum/atomic scale
- •Always confirm whether a value is per unit or total
Practical Conversion Tips
- •kWh to BTU: multiply by 3,412
- •kcal to kJ: multiply by 4.184
- •BTU to kJ: multiply by 1.055
- •Estimate: 1 kWh ≈ 860 kcal ≈ 3,412 BTU
- •Double-check food labels (EU uses kJ, US uses kcal)
Energy Examples by Category
Food & Body
- •Banana ≈ 89 kcal = 372 kJ
- •Big Mac ≈ 550 kcal = 2,301 kJ
- •Daily adult intake ≈ 2,000 kcal = 8,368 kJ
- •1 hour running ≈ 600 kcal = 2,510 kJ
- •Breastfeeding +500 kcal/day
- •Resting metabolism ≈ 1,400–1,800 kcal/day
- •100 g chocolate ≈ 546 kcal
Household & Electrical
- •LED bulb 1 hr: 0.009 kWh
- •Fridge per day: 1–2 kWh
- •Clothes dryer per load: 3.3 kWh
- •EV charge (full): 40–100 kWh
- •Air conditioner per hr: 0.5–2 kWh
- •Monthly home use: 300–1,200 kWh
- •Solar panel daily: 1–4 kWh
Industrial & Science
- •1 liter of gasoline: 34.2 MJ
- •Natural gas per cubic meter: 38.5 MJ
- •Coal per kg: 24–35 MJ
- •Nuclear fission per kg U-235: 80 × 10¹² J
- •TNT 1 kg: 4.6 MJ
- •Hiroshima bomb: ~6.3 × 10¹³ J
- •Sun output: 3.8 × 10²⁶ W
Frequently Asked Questions
What is the difference between a calorie and a kilocalorie?▾
A small calorie (cal) is the energy needed to raise 1 gram of water by 1 °C. A kilocalorie (kcal), also called a food Calorie (with capital C), equals 1,000 small calories. Nutrition labels always use kcal — so '200 Calories' means 200,000 cal = 836,800 joules. When you see 'calories' on a food package, the value is actually kilocalories.
How does energy relate to power?▾
Energy is the total amount of work done or heat transferred, while power is the rate at which energy is used or produced. Power (watts) = Energy (joules) / Time (seconds). So a 100 W bulb uses 100 joules per second, and running for 1 hour consumes 360,000 J = 0.1 kWh of energy.
What is a kilowatt-hour?▾
A kilowatt-hour (kWh) is the energy consumed by a device drawing 1 kilowatt of power for 1 hour. It equals 3,600,000 joules (3.6 MJ). Your electricity bill is measured in kWh — a typical US household uses about 900 kWh per month. One kWh can run a 60 W bulb for about 16.7 hours.
Why do scientists use electron-volts?▾
Electron-volts (eV) are used because joules are far too large for atomic and subatomic processes. One eV = 1.602 × 10⁻¹⁹ J — a conveniently sized unit at the quantum scale. Visible light photons carry 1.8–3.1 eV; chemical bonds involve 1–10 eV; nuclear reactions involve MeV to GeV. Using eV avoids writing out tiny exponents in every calculation.
How much energy does a household use per year?▾
A typical US household uses about 10,500 kWh of electricity per year (roughly 900 kWh/month). In the EU the average is closer to 3,500–5,000 kWh/year due to more efficient appliances and smaller homes. Converting: 10,500 kWh = 37.8 GJ = 35.8 million BTU. Space heating and cooling typically account for 50–70% of residential energy use.
What is the energy density of batteries vs gasoline?▾
Gasoline has an energy density of about 46 MJ/kg (12.8 kWh/kg), making it extremely energy-dense. Modern lithium-ion batteries store roughly 0.25–0.3 kWh/kg — about 40–50 times less energy per kilogram than gasoline. However, electric motors are 3–4× more efficient than combustion engines, so the effective energy gap for vehicle range is closer to 10–15×. Solid-state batteries aim to reach 0.5+ kWh/kg.