A watt-hour is 3,600 joules.
Watt-hours to kWhs Converter — Wh to kWh
Convert Watt-hour (Wh) to kWh (kWh) using the exact conversion factor (1 watt-hour = 0.001 kwh). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Watt-hours 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 3600 / 3.6e+6.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Watt-hours to kWhs
Watt-hour and kWh both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Watt-hour is typically associated with universal — standard consumer-electronics and battery energy unit worldwide, while kWh is typically associated with used worldwide for electricity billing.
Formula
kwhs = watt-hours × 0.001
This factor comes from each unit's defined relationship to the category's base unit: 1 watt-hour equals 3600 base units, and 1 kwh equals 3600000 base units, so dividing one by the other gives the direct watt-hour-to-kwh factor of 0.001.
Simple example
1 Wh × 0.001 = 0.001 kWh
1 watt-hour = 0.001 kwhs.
Real-world example
100 Wh × 0.001 = 0.1 kWh
100 watt-hours = 0.1 kwhs.
Conversion table
| Watt-hour (Wh) | kWh (kWh) |
|---|---|
| 1 Wh | 0.001 kWh |
| 10 Wh | 0.01 kWh |
| 100 Wh | 0.1 kWh |
| 500 Wh | 0.5 kWh |
| 1,000 Wh | 1 kWh |
| 2,000 Wh | 2 kWh |
Reverse conversion: kWh to Watt-hour
0.001 kWh × 1000 = 1 Wh
0.001 kwhs = 1 watt-hour.
watt-hours = kwhs × 1000
For a page dedicated to this direction, see kWh to Watt-hour.
Watt-hour vs. kWh
| Aspect | Watt-hour | kWh |
|---|---|---|
| Family | metric derived energy unit | Non-SI unit accepted for use with SI |
| Typical use | Phone, laptop, and power-bank battery capacity ratings | Residential and commercial electricity billing worldwide |
| Where it's used | Universal — standard consumer-electronics and battery energy unit worldwide | Used worldwide for electricity billing |
Understanding the Watt-hour
Watt-hour (Wh) measures energy. The energy delivered by one watt of power sustained for one hour — equal to 3,600 joules. It is classified as a metric derived energy unit.
Where it's used: Universal — standard consumer-electronics and battery energy unit worldwide
Wh vs. kWh. The same unit at different scales: 1,000 Wh equals 1 kWh. Wh suits small consumer-electronics batteries; kWh is used for household electricity billing and larger energy storage.
Uses of the Watt-hour today
- Phone, laptop, and power-bank battery capacity ratings
- Electric-vehicle battery capacity specifications
- Small-scale renewable energy (solar panel) output ratings
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.
Watt-hour — sources
- BIPM SI Brochure — Watt-hour as a common energy unit derived from the coherent SI units watt and second (via the hour).
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 watt-hour?
1 watt-hour equals 0.001 kwhs, using the exact defined conversion factor rather than an estimate.
How do I convert watt-hour to kwh?
Multiply the watt-hour value by 0.001. The converter above does this instantly to whatever precision you set.
How do I convert kwh back to watt-hour?
Use the reverse factor: 1 kwh equals 1,000 watt-hours. You can also use the swap control in the converter above to flip the direction instantly.
What is a watt-hour?
Watt-hour (Wh) measures energy. The energy delivered by one watt of power sustained for one hour — equal to 3,600 joules. It is classified as a metric derived energy 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 watt-hour 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.
What is the difference between wh vs. kwh?
The same unit at different scales: 1,000 Wh equals 1 kWh. Wh suits small consumer-electronics batteries; kWh is used for household electricity billing and larger energy storage.
Where is the watt-hour still used today?
Universal — standard consumer-electronics and battery energy unit worldwide