Calculator
What the Kilowatt Hour Converter does
Kilowatt Hour Converter: 1 kWh = 3.6 MJ, so multiply a kilowatt hour value by 3.6 to get megajoule, or divide to go back. Example: 1 kWh = 3.6 MJ.
The inputs are Value, From and To; the output is Result, How it was calculated and Reverse conversion. Change any input and the output follows immediately.
Unit mistakes are quietly expensive. They have wrecked spacecraft and ruined recipes alike. That is usually what brings students converting units for homework here.
The work is done by JavaScript already loaded in your browser, so your input never crosses the network.
The field reference, the method and a worked example using the default inputs follow the tool itself.
What do the Kilowatt Hour Converter fields mean?
The Kilowatt Hour Converter uses 3 inputs. Because the form arrives filled, the first useful result costs you zero typing.
| Field | What to enter | Default |
|---|---|---|
| Value | required | 1 |
| From | choose from Joule (J), Kilojoule (kJ), Megajoule (MJ), Calorie (thermochemical) (cal), Kilocalorie (food calorie) (kcal) or Watt hour (Wh) | Kilowatt hour (kWh) |
| To | choose from Joule (J), Kilojoule (kJ), Megajoule (MJ), Calorie (thermochemical) (cal), Kilocalorie (food calorie) (kcal) or Watt hour (Wh) | Megajoule (MJ) |
How does the Kilowatt Hour Converter work?
Both units are converted through energy's base unit (J), so any of the 12 units in the dropdowns can be paired in either direction without loss of accuracy.
Where a unit has an exact legal definition, that exact value is used rather than a rounded one. The 1959 international agreement fixing the inch at 25.4 mm is the best-known example; the same principle applies throughout.
Worked example
These are the values the Kilowatt Hour Converter loads by default, and the result it produces from them. Open the tool above and you will find precisely these figures already in place.
| Value | 1 |
|---|---|
| From | Kilowatt hour (kWh) |
| To | Megajoule (MJ) |
| Result | 3.6 MJ |
|---|---|
| How it was calculated | 1 kWh = 3.6 MJ, so 1 × 3.6 = 3.6 MJ |
| Reverse conversion | 0.27777778 kWh (if you meant 1 MJ) |
The kilowatt-hour
1 kilowatt-hour equals exactly 3,600,000 joules (3.6 megajoules). It’s the unit electricity bills are actually calculated in worldwide, representing 1 kilowatt of power sustained for 1 hour.
Worth knowing
- Power (kilowatts) and energy (kilowatt-hours) are genuinely different physical quantities despite the similar-looking names. A 1,000-watt appliance run for 1 hour uses 1 kWh, but a 2,000-watt appliance run for 30 minutes also uses exactly 1 kWh, since energy is power multiplied by time.
- This power-vs-energy confusion shows up constantly in casual conversation about electricity ("how many kilowatts did that use?" often really means kilowatt-hours), worth being precise about, since utility bills charge for kilowatt-hours, not for kilowatts.
- A rough household reference point: a typical US home uses somewhere in the range of 25 to 30 kWh per day on average, though this varies enormously by climate, home size and appliance mix.
Definitions: BIPM SI Brochure · NIST reference on units
How to use it
- Key in Value.
- Pick a value for From: the options are Joule (J), Kilojoule (kJ), Megajoule (MJ), Calorie (thermochemical) (cal), Kilocalorie (food calorie) (kcal) or Watt hour (Wh).
- Pick a value for To: the options are Joule (J), Kilojoule (kJ), Megajoule (MJ), Calorie (thermochemical) (cal), Kilocalorie (food calorie) (kcal) or Watt hour (Wh).
- No confirmation step: what you type is what gets calculated.
- Read Result, How it was calculated and Reverse conversion in the results panel.
- Use Copy Link if you want the same setup again later, or Print for a paper copy.
What this tool does not do
- Factors use the internationally agreed definitions; some industries round them differently.
- Repeated conversions compound rounding, so convert once from the original value where you can.
- There is no history: reload the page and the previous run is gone.
- A plausible-looking answer from the wrong input is still the wrong answer: verify the fields first.
Frequently asked questions
The form asks for Value, From and To. Each field is pre-filled with a sensible default, so you can change one value at a time and watch how the result responds.
With the values loaded when the page opens, result comes out as 3.6 MJ. Nudge one field at a time to see which one the answer is most sensitive to.
No. Your browser is doing the computing, so we could not see the values even if we wanted to.
Free for any use, personal or commercial.
As accurate as the inputs allow. The arithmetic itself introduces no error beyond display rounding.