A kilowatt-hour is 3.6 million joules.
kWhs to Joules Converter — kWh to J
Convert kWh (kWh) to Joule (J) using the exact conversion factor (1 kwh = 3,600,000 joule). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
kWhs to Joules converter
Converter
Energy Converter
Convert joules, calories, kilowatt-hours, BTU, electronvolts, therms, and mechanical work units.
Context values
Some unit families need one extra value for a physically accurate result.
The joule is the SI derived unit of energy.
Result = input x 3.6e+6 / 1.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting kWhs to Joules
kWh and Joule both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). kWh is typically associated with used worldwide for electricity billing, while Joule is typically associated with standard scientific and engineering energy unit worldwide.
Formula
joules = kwhs × 3600000
This factor comes from each unit's defined relationship to the category's base unit: 1 kwh equals 3600000 base units, and 1 joule equals 1 base unit, so dividing one by the other gives the direct kwh-to-joule factor of 3600000.
Simple example
1 kWh × 3600000 = 3,600,000 J
1 kwh = 3,600,000 joules.
Real-world example
100 kWh × 3600000 = 360,000,000 J
100 kwhs = 360,000,000 joules.
Conversion table
| kWh (kWh) | Joule (J) |
|---|---|
| 1 kWh | 3,600,000 J |
| 10 kWh | 36,000,000 J |
| 100 kWh | 360,000,000 J |
| 500 kWh | 1,800,000,000 J |
| 1,000 kWh | 3,600,000,000 J |
| 2,000 kWh | 7,200,000,000 J |
Reverse conversion: Joule to kWh
1 J × 2.777778e-7 = 2.777778e-7 kWh
1 joule = 2.777778e-7 kwhs.
kwhs = joules × 2.777778e-7
For a page dedicated to this direction, see Joule to kWh.
kWh vs. Joule
| Aspect | kWh | Joule |
|---|---|---|
| Family | Non-SI unit accepted for use with SI | SI derived unit |
| Typical use | Residential and commercial electricity billing worldwide | Physics and engineering energy calculations |
| Where it's used | Used worldwide for electricity billing | Standard scientific and engineering energy unit worldwide |
Understanding the kWh
kWh (kWh) measures energy. A kilowatt-hour is the energy of one kilowatt of power sustained for one hour: exactly 3,600,000 joules. It is classified as a Non-SI unit accepted for use with SI.
Where it's used: Used worldwide for electricity billing
Uses of the kWh today
- Residential and commercial electricity billing worldwide
- Battery capacity ratings (especially electric vehicles)
- Energy policy and grid-scale power statistics
History of the kWh
The kilowatt-hour became the standard electricity billing unit as power utilities expanded in the late 19th and early 20th centuries, since it conveniently matches the scale of typical household electricity consumption, unlike the much smaller joule.
Historical origin. kWh was not the invention of a single named person; it developed through the process described above.
Understanding the Joule
Joule (J) measures energy. The joule is the SI derived unit of energy, defined as the work done by one newton acting over one meter. It is classified as a SI derived unit.
Where it's used: Standard scientific and engineering energy unit worldwide
Uses of the Joule today
- Physics and engineering energy calculations
- Electrical energy in scientific contexts (though kWh is used for billing)
- Nutrition labeling in some countries (alongside or instead of calories)
History of the Joule
The joule is named after English physicist James Prescott Joule, whose experiments in the 1840s established the mechanical equivalent of heat — demonstrating that mechanical work and heat are interchangeable forms of energy, foundational to the first law of thermodynamics.
The unit itself was formally adopted as the SI derived unit of energy by international agreement as part of the broader SI system, defined coherently from the base units (kg, m, s) rather than as an independent physical standard.
Historical origin. Joule was not the invention of a single named person; it developed through the process described above.
kWh — sources
- BIPM SI Brochure — Non-SI units accepted for use with SI — Lists the kilowatt-hour among accepted non-SI energy units.
Joule — sources
- BIPM SI Brochure — Coherent derived units — Defines the joule as the SI unit of energy.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many joules are in 1 kwh?
1 kwh equals 3,600,000 joules, using the exact defined conversion factor rather than an estimate.
How do I convert kwh to joule?
Multiply the kwh value by 3600000. The converter above does this instantly to whatever precision you set.
How do I convert joule back to kwh?
Use the reverse factor: 1 joule equals 2.777778e-7 kwhs. You can also use the swap control in the converter above to flip the direction instantly.
What is a kwh?
kWh (kWh) measures energy. A kilowatt-hour is the energy of one kilowatt of power sustained for one hour: exactly 3,600,000 joules. It is classified as a Non-SI unit accepted for use with SI.
What is a joule?
Joule (J) measures energy. The joule is the SI derived unit of energy, defined as the work done by one newton acting over one meter. It is classified as a SI derived unit.
Is the kwh to joule conversion exact?
Yes. A kilowatt-hour is the energy of one kilowatt of power sustained for one hour: exactly 3,600,000 joules. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the kwh still used today?
Used worldwide for electricity billing