Femtojoule is 1e-15 joule units.
Femtojoules to kWhs Converter — fJ to kWh
Convert Femtojoule (fJ) to kWh (kWh) using the exact conversion factor (1 femtojoule = 2.777778e-22 kwh). See the formula, worked examples, conversion table, history, and common uses.
Femtojoules 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 1e-15 / 3.6e+6.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Femtojoules to kWhs
Femtojoule and kWh both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Specifically: Femtojoule is 1e-15 joule units, and a kilowatt-hour is 3.6 million joules.
Formula
kwhs = femtojoules × 2.777778e-22
This factor comes from each unit's defined relationship to the category's base unit: 1 femtojoule equals 1e-15 base units, and 1 kwh equals 3600000 base units, so dividing one by the other gives the direct femtojoule-to-kwh factor of 2.777778e-22.
Simple example
1 fJ × 2.777778e-22 = 2.777778e-22 kWh
1 femtojoule = 2.777778e-22 kwhs.
Real-world example
100 fJ × 2.777778e-22 = 2.777778e-20 kWh
100 femtojoules = 2.777778e-20 kwhs.
Conversion table
| Femtojoule (fJ) | kWh (kWh) |
|---|---|
| 1 fJ | 2.777778e-22 kWh |
| 10 fJ | 2.777778e-21 kWh |
| 100 fJ | 2.777778e-20 kWh |
| 500 fJ | 1.388889e-19 kWh |
| 1,000 fJ | 2.777778e-19 kWh |
| 2,000 fJ | 5.555556e-19 kWh |
Reverse conversion: kWh to Femtojoule
2.777778e-22 kWh × 3.6e+21 = 1.00000008 fJ
2.777778e-22 kwhs = 1.00000008 femtojoules.
femtojoules = kwhs × 3.6e+21
For a page dedicated to this direction, see kWh to Femtojoule.
Understanding the Femtojoule (fJ)
Femtojoule is 1e-15 joule units.
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.
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 femtojoule?
1 femtojoule equals 2.777778e-22 kwhs, using the exact defined conversion factor rather than an estimate.
How do I convert femtojoule to kwh?
Multiply the femtojoule value by 2.777778e-22. The converter above does this instantly to whatever precision you set.
How do I convert kwh back to femtojoule?
Use the reverse factor: 1 kwh equals 3.6e+21 femtojoules. You can also use the swap control in the converter above to flip the direction instantly.
What is a femtojoule?
Femtojoule (fJ) is a unit of energy.
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 femtojoule 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.