Reference table
Battery capacity: mAh and Wh
Milliampere hours measure charge, watt hours measure energy. They are linked only through voltage: Wh = Ah × volts. That is why two batteries with identical mAh are not automatically equal in size.
| Charge (mAh) | Charge (Ah) | Energy at 3.7 V | Energy at 5 V | Energy at 12 V |
|---|---|---|---|---|
| 500 | 0.5 Ah | 0.0037 Wh | 0.005 Wh | 0.012 Wh |
| 1,000 | 1 Ah | 0.0037 Wh | 0.005 Wh | 0.012 Wh |
| 2,000 | 2 Ah | 0.0037 Wh | 0.005 Wh | 0.012 Wh |
| 3,000 | 3 Ah | 0.0037 Wh | 0.005 Wh | 0.012 Wh |
| 5,000 | 5 Ah | 0.0037 Wh | 0.005 Wh | 0.012 Wh |
| 10,000 | 10 Ah | 0.0037 Wh | 0.005 Wh | 0.012 Wh |
| 20,000 | 20 Ah | 0.0037 Wh | 0.005 Wh | 0.012 Wh |
The voltages are typical nominal values, not measurements: lithium-ion cells usually sit at 3.6 to 3.7 V, USB at 5 V, vehicle systems at 12 V. The actual value depends on cell chemistry and state of charge, so a Wh figure is only meaningful together with its voltage. Energy in Wh is the more robust basis for comparison than mAh.