Convert Joules to Watt-hours
1 joule (J) equals 0.0002777777778 watt-hours (Wh).
1 J = 0.0002777777778 Wh
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk joule to watt-hour converter to paste a column from Excel.
How to Convert Joule to Watt-hour
- 1 J = 0.0002777777778 Wh
- 1 Wh = 3600 J
- Example: convert 15 J to Wh: 15 J = 15 × 0.0002777777778 Wh = 0.004166666667 Wh
Formula
Wh = J ÷ 3600
Derivation from SI units:
- 1 J = 1 N·m = 1 W·s = 1 kg·m²·s⁻²
- 1 Wh = 1 W × 3600 s = 3600 J
Both units are defined exactly, so the factor is exact. Joule definition: joule; Watt-hour definition: watt-hour.
Worked examples
- 3600 J is exactly 1 Wh.
3600 J × 0.0002777777778 = 1 Wh - 50000 J is 13.88888889 Wh.
50000 J × 0.0002777777778 = 13.88888889 Wh
Joule to Watt-hour conversion table
| Joules (J) | Watt-hours (Wh) |
|---|---|
| 1 J | 0.0002777777778 Wh |
| 10 J | 0.002777777778 Wh |
| 100 J | 0.02777777778 Wh |
| 250 J | 0.06944444444 Wh |
| 500 J | 0.1388888889 Wh |
| 1000 J | 0.2777777778 Wh |
| 4184 J | 1.162222222 Wh |
| 10000 J | 2.777777778 Wh |
| 100000 J | 27.77777778 Wh |
| 1000000 J | 277.7777778 Wh |
| 3600000 J | 1000 Wh |
Where it's used
Joule values are converted to watt-hours to compare with battery and appliance energy ratings. Divide by 3600.
Joule to other energy units
| Conversion | 1 J equals |
|---|---|
| joule to kilojoule | 0.001 kJ |
| joule to megajoule | 0.000001 MJ |
| joule to calorie | 0.2390057361 cal |
| joule to kilocalorie | 0.0002390057361 kcal |
| joule to watt-hour | 0.0002777777778 Wh |
| joule to kilowatt-hour | 2.777777778 × 10⁻⁷ kWh |
| joule to BTU | 0.0009478171203 BTU |
| joule to therm | 9.48043428 × 10⁻⁹ thm |
| joule to electronvolt | 6.241509074 × 10¹⁸ eV |
| joule to foot-pound | 0.7375621493 ft·lbf |
| joule to erg | 10000000 erg |
Frequently asked questions
How do I convert joules to Wh?
Divide by 3600: 7200 J = 2 Wh.
How many watt-hours are in 1 joule?
1 J = 0.0002777777778 Wh.
How do I convert joules to watt-hours?
Multiply the value in J by 0.0002777777778, or divide it by 3600. For example, 15 J × 0.0002777777778 = 0.004166666667 Wh.
Is the J to Wh conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4, coherent derived units with special names.
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "watt hour (W·h)".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Joules to Watt-hours. Retrieved October 17, 2026, from https://scientificconverters.com/energy/joules-to-watt-hours/
IEEE
Scientific Converters, "Convert Joules to Watt-hours," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/energy/joules-to-watt-hours/