Watt-Hours to Amp-Hours Calculator
Convert energy in watt-hours (Wh) back to battery capacity in amp-hours (Ah) using the system voltage.
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Ah
Formula: Ah = Wh ÷ V
How to convert Wh to Ah
The formula is Ah = Wh / V.
For example, 1200 Wh at 12V = 100 Ah; the same 1200 Wh at 24V = 50 Ah. This shows why voltage is strictly required when determining capacity.
Common Wh to Ah Conversions
| Watt-Hours (Wh) | 12V System | 24V System | 48V System |
|---|---|---|---|
| 500 Wh | 41.67 Ah | 20.83 Ah | 10.42 Ah |
| 1000 Wh | 83.33 Ah | 41.67 Ah | 20.83 Ah |
| 1200 Wh | 100.00 Ah | 50.00 Ah | 25.00 Ah |
| 2000 Wh | 166.67 Ah | 83.33 Ah | 41.67 Ah |
| 5000 Wh | 416.67 Ah | 208.33 Ah | 104.17 Ah |
Frequently Asked Questions
Why does the Ah change with voltage?
Amp-hours measure charge, while watt-hours measure total energy. To get the same total energy at a higher voltage, you need fewer amp-hours.
Can I convert without knowing voltage?
No, the conversion is meaningless without system voltage.
Is this used for lithium batteries?
Yes, but always use the nominal voltage (e.g. 12.8V for LiFePO4) for the most accurate calculation.