Electrical energy
1 kilowatt-hour is exactly 3.6 megajoules, or 3,600,000 joules. The hour contributes the factor of 3,600 seconds.
Energy Converter
A food Calorie means one thermochemical kilocalorie here (4,184 J). Btu uses the International Table definition, not thermochemical or temperature-specific Btu.
Converted value
Megajoules (MJ)
Megajoules (MJ)
Display rounding does not change the calculation. Scientific notation keeps very small values visible; extra digits do not add measurement accuracy.
| Unit | Equivalent |
|---|---|
| Joules (J) | 3600000 |
| Kilojoules (kJ) | 3600 |
| Megajoules (MJ) | 3.6 |
| Watt-hours (Wh) | 1000 |
| Kilowatt-hours (kWh) | 1 |
| Thermochemical calories (cal) | 860420.65 |
| Thermochemical kilocalories (kcal / food Cal) | 860.42065 |
| International Table calories (cal IT) | 859845.228 |
| International Table Btu (Btu IT) | 3412.14163 |
| Foot pound-force (ft·lbf) | 2655223.74 |
| Electronvolts (eV) | 2.24694327e+25 |
Appliance energy over a usage period
Assumes a constant average input power. Use measured average watts for cycling appliances; this does not infer efficiency or energy prices.
90Energy (kWh)
324Megajoules (MJ)
60Operating time (h)
All entered measurements and calculations stay in this browser. No external API or uploaded dataset is used.
How to use the Energy Converter
- 01
Enter a numeric value without a comma separator or unit suffix, then choose the source and destination units.
- 02
Read the main result and equivalent-unit table. Choose 3, 6, 9, or 12 significant digits for display; calculation constants are not rounded to match the display.
- 03
Use the appliance energy over a usage period panel for the practical calculation. Restore its example independently from the converter.
- 04
Copy the conversion or task results, or download the displayed conversion table as a CSV. Clear removes the converter value.
Examples
An appliance schedule
A 1,500 W device used for 2 hours per day over 30 days consumes 90 kWh if its average draw stays at that level.
Power multiplied by time
Energy measures an amount; power measures the rate at which energy is transferred. Multiply watts by seconds to obtain joules, or kilowatts by hours to obtain kilowatt-hours. A device nameplate can describe maximum rather than average draw.
Calories and Btu need a definition
A thermochemical calorie is exactly 4.184 J; the International Table calorie is exactly 4.1868 J. This tool keeps them separate. Its food Calorie option is a thermochemical kilocalorie, and its Btu option is International Table Btu at 1,055.05585262 J.
Precision and accepted input
Use a decimal point or scientific notation such as 1e3. Blank values, unit suffixes, separators, and nonfinite numbers are rejected. Input magnitudes above 1e100 or nonzero magnitudes below 1e-100 are outside the supported range. The table rounds only for presentation, so 12 displayed digits should not be interpreted as 12 digits of measurement accuracy. Binary floating-point calculations can differ from exact decimal arithmetic in the final digits.
What to know
- Selected named units only; no fuel-equivalent, nutritional, or tariff model.
- Appliance energy assumes constant average power and excludes startup or standby unless included in that average.
Common questions
Is kW the same as kWh?
No. kW is power and kWh is energy. A 1 kW load operating for 2 hours transfers 2 kWh of energy.
Does food energy predict a body-weight change?
No. The calorie options convert units only. They do not model nutrition, metabolism, or changes in body mass.