Wh to Ah Calculator
Convert watt-hours (Wh) to amp-hours (Ah) by dividing by the battery voltage: Ah = Wh ÷ V. Compare batteries of different voltages or size a battery bank.
CAPACITY
100 Ah
IN mAh
100,000 mAh
FORMULA
Ah = Wh / V
💡 How to Convert Wh to Ah
To convert watt-hours to amp-hours, divide the watt-hours by the battery's nominal voltage. Watt-hours measure stored energy; amp-hours measure charge. The voltage links them, so the same energy gives more amp-hours at a lower voltage.
Wh to Ah formula
Example: 1,200 Wh at 12 V → 1,200 ÷ 12 = 100 Ah
Worked examples
- Solar battery bank: you need 2,400 Wh of storage on a 24 V system: 2,400 ÷ 24 = 100 Ah.
- Same energy at 12 V: 2,400 ÷ 12 = 200 Ah, twice the amp-hours for the same stored energy.
- Laptop battery: 60 Wh on a 11.4 V pack = 60 ÷ 11.4 = 5.26 Ah (5,263 mAh).
Wh to Ah table
| Wh | 3.7 V | 12 V | 12.8 V | 24 V | 48 V |
|---|---|---|---|---|---|
| 100 | 27 | 8.3 | 7.8 | 4.2 | 2.1 |
| 500 | 135.1 | 41.7 | 39.1 | 20.8 | 10.4 |
| 1,000 | 270.3 | 83.3 | 78.1 | 41.7 | 20.8 |
| 1,200 | 324.3 | 100 | 93.8 | 50 | 25 |
| 2,000 | 540.5 | 166.7 | 156.2 | 83.3 | 41.7 |
| 2,400 | 648.6 | 200 | 187.5 | 100 | 50 |
| 5,000 | 1,351.4 | 416.7 | 390.6 | 208.3 | 104.2 |
| 10,000 | 2,702.7 | 833.3 | 781.2 | 416.7 | 208.3 |
Which voltage to use
Use the battery's nominal voltage, the figure printed on the label, not the voltage you measure at full charge. Common values:
- Lithium-ion cell (phones, laptops, power banks): 3.6–3.7 V per cell.
- LiFePO4 (lithium iron phosphate): 3.2 V per cell, so a 4-cell "12 V" pack is 12.8 V.
- Lead-acid: 2 V per cell, so 12 V for a 6-cell battery.
- Battery banks for solar and backup systems: usually 12 V, 24 V or 48 V.
Sizing a battery from a daily load
Add up the watt-hours you use per day (watts × hours for each device), divide by your inverter efficiency (for example 0.9), divide by the usable depth of discharge (for example 0.5 for lead-acid or 0.8 for LiFePO4), then convert to Ah at your system voltage.