Convert between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, and BTUs. Useful for science, nutrition, and energy cost comparisons.
Joules
3,600,000 J
Kilojoules
3,600 kJ
Calories
860,420.65 cal
Kilocalories
860.4207 kcal
Watt-hours
1,000 Wh
Kilowatt-hours
1 kWh
BTU
3,412.13 BTU
AA Battery
250.0×
Single AA cell
Food Calorie
860.4×
1 dietary Calorie
Candy Bar
3.4×
~250 kcal snack
Gallon of Gas
0.027×
Gasoline energy
Daily Diet (2000 kcal)
0.430×
Average intake
Running 1 Hour
1.4×
~600 kcal burned
90.0
Phone charges
Full smartphone charge (~40 kJ)
100.0
LED bulb hours
10W LED bulb runtime
20.0
Laptop hours
50W laptop runtime
50.0
Microwave minutes
1200W microwave
3.3
Electric car miles
~0.3 kWh per mile
0.25
Hot showers (8 min)
~4 kWh per shower
Energy is measured in many different units across various fields. Joules and kilojoules are the SI standard used in physics. Calories and kilocalories are used in nutrition. Kilowatt-hours are how electricity is billed. BTUs are used for heating and cooling systems. This converter lets you quickly switch between all these common energy units.
A kilocalorie (kcal) is 1,000 calories. When food labels say "Calories" (with a capital C), they actually mean kilocalories. So a 200-Calorie snack contains 200 kcal or 200,000 small calories.
Multiply the kWh value by 3,600,000 (or 3.6 × 10⁶). One kilowatt-hour equals 3.6 megajoules. This conversion is useful when comparing electricity costs to other energy sources.
A British Thermal Unit (BTU) is the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit. BTUs are commonly used in the US to rate heating and cooling systems. One BTU equals approximately 1,055 joules.
Power Converter
Convert between watts, kilowatts, horsepower, BTU per hour, and foot-pounds per second. Useful for comparing engines, motors, and electrical equipment.
Unit Converter
Convert between common units of length, weight, temperature, and volume instantly. Select a category, enter your value, and see the result in real time.