Joules to Watt-hours Converter
Enter the energy in joules below to convert it to watt-hours.
Convert Joules to Watt-hours
Enter a value in joules (J) to convert to watt-hours (Wh).
Joule to Watt-hour Conversion Table
Table showing various joule measurements converted to watt-hours. Click any preset value or arrow to load it into the converter.
| Joules (J) | Watt-hours (Wh) |
|---|---|
| 1 J | 0.000277778 Wh |
| 2 J | 0.000555556 Wh |
| 2.5 J | 0.000694444 Wh |
| 5 J | 0.0013889 Wh |
| 10 J | 0.0027778 Wh |
| 15 J | 0.0041667 Wh |
| 20 J | 0.0055556 Wh |
| 25 J | 0.0069444 Wh |
| 30 J | 0.0083333 Wh |
| 50 J | 0.0138889 Wh |
How to Convert Joules to Watt-hours
To convert joules to watt-hours, multiply the energy by the following conversion ratio: 0.000277778 watt-hours/joule.
Since one joule is equal to 0.000277778 watt-hours, you can use this simple formula to convert:
The energy in watt-hours is equal to the energy in joules multiplied by 0.000277778.
For example, here's how to convert 5 joules to watt-hours using the formula above.
How Many Watt-hours Are in a Joule?
There are 0.000277778 watt-hours in a joule, which is why we use this value in the formula above.
Our joule to watt-hour calculator automatically converts your energy measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Joules and watt-hours are both units used to measure energy. Keep reading to learn more about each unit.
What Is a Joule?
Coherent SI unit of energy and work (1 W·s = 1 N·m). It serves as a primary reference unit for measuring energy across scientific and practical applications. [1]
The joule is classified as an International System of Units (SI) unit of energy. Joules can be abbreviated as J; for example, 1 joule can be written as 1 J.
As the primary coherent reference unit for energy in this category, all other energy units are mathematically anchored to the joule (J).
In practice, joules (J) are widely used across standard energy applications within International System of Units (SI) workflows, engineering documentation, and technical data sheets.
What Is a Watt-hour?
A watt-hour is a unit of energy equal to 3,600 joules (J), the base unit for energy. Equal to 3,600 Joules. [2]
The watt-hour is classified as a metric and SI-compatible unit of energy. Watt-hours can be abbreviated as Wh; for example, 1 watt-hour can be written as 1 Wh.
When working with watt-hours (Wh) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, watt-hours (Wh) are widely used across large-scale industrial, bulk, and macro-level energy specifications within SI metric workflows, engineering documentation, and technical data sheets.
When converting energy between joules (J) and watt-hours (Wh), keep full floating-point precision (1 J = 0.000277778 Wh; 1 Wh = 3,600 J) during intermediate calculations and round only the final watt-hour figure to match your instrument tolerance.
More Joule & Watt-hour Conversions
Need to calculate in the opposite direction? Use our watt-hours to joules calculator to switch your starting unit immediately. You can also explore related tools such as converting watt-hours to joules, converting ampere-hours to watt-hours, or converting milliampere-hours to watt-hours.
Convert from Joules
Frequently Asked Questions
References
- [1]NIST CODATA StandardNIST CODATA (CODATA Energy & Thermodynamic Constants)·Energy Metrology Standard — Joules (J) to Watt-hours (Wh)
- [2]NIST SP 811 SpecificationNIST SP 811 (NIST SP 811 App. B.9 (Energy, Work & Heat))·Unit Specifications: Joule (J) & Watt-hour (Wh)
- [3]BIPM ReferenceBIPM (Derived SI Unit: Joule (J))·Conversion Factors & Mathematical Basis (J to Wh)