Watt-hours to Joules Converter
Common Conversions
| Wh | J |
|---|---|
| 0.001 | 3.6 |
| 0.01 | 36 |
| 0.1 | 360 |
| 1 | 3600 |
| 5 | 18000 |
| 10 | 36000 |
| 100 | 360000 |
| 500 | 1800000 |
| 1000 | 3600000 |
| 5000 | 18000000 |
| 10000 | 36000000 |
Why this conversion matters in chemistry
Lithium-ion cell-chemistry calculations is the usual setting. A 21700-format cell rated at 15,000 mWh = 15 Wh on the datasheet converts to 54,000 J — entered into a specific-energy calculation (J/g or J/kg) when comparing NMC-811 chemistry against LFP against the theoretical Li-metal anode limit. The constant of 3600 J per Wh is exact through the SI definitions. The conversion lets the cell-level Wh rating land in the joule form Gibbs-energy and Pourbaix-style electrochemistry calculations actually use.
Formula
J = Wh × 3600
Worked Examples
1 Wh = 3600 J
The conversion anchor — 1 watt for 1 hour.
7.4 Wh = 26,640 J
About a typical 18650 cell at 3.7 V × 2 Ah.
1000 Wh = 3.6 × 10⁶ J
1 kWh in joules — about a household-scale energy unit.
0.1 Wh = 360 J
About the energy budget of a coin cell.
Frequently Asked Questions
How do I convert Wh to joules?
Multiply by 3600. So 1 Wh becomes 3600 J. The factor is exact through the SI definitions of the watt and the hour.
Why is 1 Wh = 3600 J?
One watt is one joule per second. Over one hour (3600 seconds), 1 W × 3600 s = 3600 J. The relationship is definitional, not empirical.
What are typical battery energies in Wh and J?
AA cell: about 4.2 Wh (15,120 J). Phone battery: about 11.5 Wh (41,400 J). Laptop battery: about 50 Wh (180,000 J). The Wh form lives on datasheets; the joule form lands in physics-style energy budgets.
How does Wh relate to electrochemistry?
Battery energy in Wh connects to Gibbs free energy via ΔG = −nFE. The Wh rating is the macroscopic accounting of the same per-electron energy the cell-reaction half-reactions produce.