The joule is the SI derived unit of energy.
Joules to kWhs Converter — J to kWh
Convert Joule (J) to kWh (kWh) using the exact conversion factor (1 joule = 2.777778e-7 kwh). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Joules to kWhs 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.
A kilowatt-hour is 3.6 million joules.
Result = input x 1 / 3.6e+6.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Joules to kWhs
Joule and kWh both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Joule is typically associated with standard scientific and engineering energy unit worldwide, while kWh is typically associated with used worldwide for electricity billing.
Formula
kwhs = joules × 2.777778e-7
This factor comes from each unit's defined relationship to the category's base unit: 1 joule equals 1 base unit, and 1 kwh equals 3600000 base units, so dividing one by the other gives the direct joule-to-kwh factor of 2.777778e-7.
Simple example
1 J × 2.777778e-7 = 2.777778e-7 kWh
1 joule = 2.777778e-7 kwhs.
Real-world example
100 J × 2.777778e-7 = 0.0000277778 kWh
100 joules = 0.0000277778 kwhs.
Conversion table
| Joule (J) | kWh (kWh) |
|---|---|
| 1 J | 2.777778e-7 kWh |
| 10 J | 0.0000027778 kWh |
| 100 J | 0.0000277778 kWh |
| 500 J | 0.0001388889 kWh |
| 1,000 J | 0.0002777778 kWh |
| 2,000 J | 0.0005555556 kWh |
Reverse conversion: kWh to Joule
2.777778e-7 kWh × 3600000 = 1.00000008 J
2.777778e-7 kwhs = 1.00000008 joules.
joules = kwhs × 3600000
For a page dedicated to this direction, see kWh to Joule.
Joule vs. kWh
| Aspect | Joule | kWh |
|---|---|---|
| Family | SI derived unit | Non-SI unit accepted for use with SI |
| Typical use | Physics and engineering energy calculations | Residential and commercial electricity billing worldwide |
| Where it's used | Standard scientific and engineering energy unit worldwide | Used worldwide for electricity billing |
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.
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.
Joule — sources
- BIPM SI Brochure — Coherent derived units — Defines the joule as the SI unit of energy.
kWh — sources
- BIPM SI Brochure — Non-SI units accepted for use with SI — Lists the kilowatt-hour among accepted non-SI energy units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many kwhs are in 1 joule?
1 joule equals 2.777778e-7 kwhs, using the exact defined conversion factor rather than an estimate.
How do I convert joule to kwh?
Multiply the joule value by 2.777778e-7. The converter above does this instantly to whatever precision you set.
How do I convert kwh back to joule?
Use the reverse factor: 1 kwh equals 3,600,000 joules. You can also use the swap control in the converter above to flip the direction instantly.
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.
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.
Is the joule to kwh 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 joule still used today?
Standard scientific and engineering energy unit worldwide