Energy Converter
Convert between different energy units including joules, calories, BTU, and more
Energy Converter
Common Conversions
Energy Examples
Household Energy
- • Average home daily use: ~30 kWh
- • LED bulb (10W, 1 hour): 36 kJ
- • Microwave (1000W, 2 min): 120 kJ
- • Electric car (100 miles): ~30 kWh
Food Energy
- • Apple: ~350 kJ (80 kcal)
- • Slice of bread: ~315 kJ (75 kcal)
- • Can of soda: ~590 kJ (140 kcal)
- • Daily intake: ~8400 kJ (2000 kcal)
Energy Unit Reference
Scientific Units
- • Joule (J): SI base unit of energy
- • Calorie (cal): Energy to heat 1g water by 1°C
- • Electron Volt (eV): Atomic scale energy
- • Erg: CGS unit (very small)
Practical Units
- • kWh: Electrical energy billing
- • BTU: Heating/cooling systems
- • Therm: Natural gas billing
- • kcal: Food energy (Calories)
Understanding Energy Conversions
Energy conversions relate joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours and BTU. The joule is the SI unit, and all other units are fixed multiples of it.
Two everyday contexts dominate these searches. In nutrition, the "Calorie" on food labels is actually a kilocalorie (1 kcal = 4,184 J). In electricity, energy is billed in kilowatt-hours (1 kWh = 3,600,000 J), which is why converting kWh to joules or BTU is common for appliance and heating calculations.
Frequently Asked Questions
How many joules are in a calorie?
One small calorie equals 4.184 joules. One food Calorie (kilocalorie) equals 4,184 joules.
How many joules are in a kilowatt-hour?
One kilowatt-hour equals 3,600,000 joules (3.6 megajoules).
What is a BTU in joules?
One British Thermal Unit (BTU) equals approximately 1,055.06 joules.
Is a food Calorie the same as a calorie?
No. A food Calorie (with a capital C) is a kilocalorie, equal to 1,000 small calories.