Attojoule is 1e-18 joule units.
Attojoules to Watt-hours Converter — aJ to Wh
Convert Attojoule (aJ) to Watt-hour (Wh) using the exact conversion factor (1 attojoule = 2.777778e-22 watt-hour). See the formula, worked examples, conversion table, and common uses.
Attojoules to Watt-hours converter
Converter
Engineering Converter
Convert common stress, force, torque, power, and energy units used in engineering.
Context values
Some unit families need one extra value for a physically accurate result.
A watt-hour is 3,600 joules.
Result = input x 1e-18 / 3600.
Energy units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Attojoules to Watt-hours
Attojoule and Watt-hour both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. Specifically: Attojoule is 1e-18 joule units, and a watt-hour is 3,600 joules.
Formula
watt-hours = attojoules × 2.777778e-22
This factor comes from each unit's defined relationship to the category's base unit: 1 attojoule equals 1e-18 base units, and 1 watt-hour equals 3600 base units, so dividing one by the other gives the direct attojoule-to-watt-hour factor of 2.777778e-22.
Simple example
1 aJ × 2.777778e-22 = 2.777778e-22 Wh
1 attojoule = 2.777778e-22 watt-hours.
Real-world example
100 aJ × 2.777778e-22 = 2.777778e-20 Wh
100 attojoules = 2.777778e-20 watt-hours.
Conversion table
| Attojoule (aJ) | Watt-hour (Wh) |
|---|---|
| 1 aJ | 2.777778e-22 Wh |
| 10 aJ | 2.777778e-21 Wh |
| 50 aJ | 1.388889e-20 Wh |
| 100 aJ | 2.777778e-20 Wh |
| 500 aJ | 1.388889e-19 Wh |
| 1,000 aJ | 2.777778e-19 Wh |
Reverse conversion: Watt-hour to Attojoule
2.777778e-22 Wh × 3.6e+21 = 1.00000008 aJ
2.777778e-22 watt-hours = 1.00000008 attojoules.
attojoules = watt-hours × 3.6e+21
For a page dedicated to this direction, see Watt-hour to Attojoule.
Understanding the Attojoule (aJ)
Attojoule is 1e-18 joule units.
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
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).
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many watt-hours are in 1 attojoule?
1 attojoule equals 2.777778e-22 watt-hours, using the exact defined conversion factor rather than an estimate.
How do I convert attojoule to watt-hour?
Multiply the attojoule value by 2.777778e-22. The converter above does this instantly to whatever precision you set.
How do I convert watt-hour back to attojoule?
Use the reverse factor: 1 watt-hour equals 3.6e+21 attojoules. You can also use the swap control in the converter above to flip the direction instantly.
What is a attojoule?
Attojoule (aJ) is a unit of engineering.
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.
Is the attojoule to watt-hour conversion exact?
Yes. Both attojoule and watt-hour are defined by fixed standards rather than physical artifacts, so the factor of 2.777778e-22 used above is exact to as many digits as you choose to display.
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.