Energy Converter
Convert between joules, calories, kilowatt-hours, BTUs, and more.
Energy converter card
Enter an energy value and choose the units to convert between.
Supports decimals, zero, and scientific notation.
Scientific notation appears when helpful.
Converted energy value
3,600,000 J
1 kWh converted to Joules.
Original value
1 kWh
Kilowatt-hours
Conversion factor
1 kWh = 3,600,000 J
Source unit to target unit.
Equivalent joules
3,600,000 J
All conversions use joules as the base unit.
Equivalent kWh
1 kWh
Useful for electricity and battery calculations.
Rounded result
3,600,000 J
Quick readable display.
Exact factor basis
3600000 J / 1 J
Source factor divided by target factor.
Local conversion
All conversions run instantly in the browser using joules as the base unit.
Science friendly
Includes joules, calories, electronvolts, foot-pounds, BTU, and therms.
Electricity ready
Convert Wh and kWh for batteries, appliances, electricity use, and energy estimates.
Dynamic Conversion Insights
All Common Energy Equivalents
Common Energy Units Explained
Joule (J)
The SI base-derived unit for energy, work, and heat.
Kilojoule (kJ)
Common for food energy, chemistry, and practical science calculations.
Megajoule (MJ)
Useful for larger engineering, fuel, and electricity-scale values.
Calorie (cal)
A small physics calorie. Nutrition Calories usually mean kilocalories.
Kilocalorie / food Calorie (kcal)
The food Calorie used on many nutrition labels.
Watt-hour (Wh)
Common for batteries, small appliances, and device energy use.
Kilowatt-hour (kWh)
The standard unit for electricity bills and home energy use.
British thermal unit (BTU)
Common in heating, cooling, HVAC, and fuel-energy contexts.
Therm (therm)
Used for natural gas billing in some regions.
Foot-pound (ft-lb)
A mechanical work and energy unit.
Electronvolt (eV)
Common for atomic, nuclear, and particle-scale energy.
Joules, Calories, Watt-Hours, BTU, and Therms Explained
Joule
The SI unit of energy, used across science and engineering.
Calorie and kilocalorie
Common in food, heat, nutrition, and chemistry contexts.
Watt-hour and kWh
Common for electricity, batteries, appliances, and energy bills.
BTU
Common for heating, cooling, HVAC, and thermal systems.
Therm
Common for natural gas billing in some regions.
Electronvolt
Common for atomic, nuclear, and particle physics.
Energy vs Power Explained
Energy
Energy is the amount of work or heat transferred. Joules, calories, watt-hours, and kilowatt-hours measure energy.
Power
Power is the rate of using or producing energy. Watts and kilowatts measure power.
Example: Power 1,000 W × time 2 hours = energy used 2 kWh.
Food Calories vs Physics Calories
Small calorie, cal
A small calorie equals 4.184 joules. It is often used in scientific heat calculations.
Food Calorie, kcal
A food Calorie usually means 1 kilocalorie. 1 food Calorie = 1 kcal = 4,184 joules.
Common Energy Conversion Examples
| Conversion | Equivalent |
|---|---|
| 1 J | 1 joule |
| 1 kJ | 1,000 J |
| 1 cal | 4.184 J |
| 1 kcal | 4,184 J |
| 1 Wh | 3,600 J |
| 1 kWh | 3,600,000 J |
| 1 BTU | ≈ 1,055.06 J |
| 1 therm | ≈ 105.506 MJ |
| 1 ft-lb | ≈ 1.35582 J |
Practical Energy Use Cases
Formula Explanation
Converted Energy = Input Energy × Conversion Factor
Base Joules = Input Value × Source Unit Factor
Target Value = Base Joules ÷ Target Unit Factor
J = kWh × 3,600,000
kWh = J ÷ 3,600,000
J = cal × 4.184
J = kcal × 4,184
J = BTU × 1,055.05585262
The input value is converted from the source unit into joules, then from joules into the target unit. The displayed result is rounded using your selected precision.
Frequently Asked Questions
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