Ah to Wh Calculator
Convert amp-hours (Ah) to watt-hours (Wh) by multiplying by the battery voltage: Wh = Ah × V. Find out how much energy a battery really stores.
ENERGY
1,200 Wh
IN kWh
1.2 kWh
FORMULA
Wh = Ah × V
💡 How to Convert Ah to Wh
To convert amp-hours to watt-hours, multiply the amp-hours by the battery's nominal voltage. Watt-hours are the better way to compare batteries, because they measure the energy stored regardless of voltage.
Ah to Wh formula
Example: 100 Ah at 12 V → 100 × 12 = 1,200 Wh
Worked examples
- 12 V lead-acid leisure battery, 100 Ah: 100 × 12 = 1,200 Wh; at 50% depth of discharge about 600 Wh is usable.
- 12.8 V LiFePO4, 100 Ah: 100 × 12.8 = 1,280 Wh; at 90% depth of discharge about 1,152 Wh is usable.
- 48 V server-rack battery, 100 Ah (51.2 V nominal): 100 × 51.2 = 5,120 Wh (5.12 kWh).
Ah to Wh table
| Ah | 12 V | 12.8 V | 24 V | 25.6 V | 48 V | 51.2 V |
|---|---|---|---|---|---|---|
| 7 | 84 | 89.6 | 168 | 179.2 | 336 | 358.4 |
| 20 | 240 | 256 | 480 | 512 | 960 | 1,024 |
| 50 | 600 | 640 | 1,200 | 1,280 | 2,400 | 2,560 |
| 100 | 1,200 | 1,280 | 2,400 | 2,560 | 4,800 | 5,120 |
| 120 | 1,440 | 1,536 | 2,880 | 3,072 | 5,760 | 6,144 |
| 150 | 1,800 | 1,920 | 3,600 | 3,840 | 7,200 | 7,680 |
| 200 | 2,400 | 2,560 | 4,800 | 5,120 | 9,600 | 10,240 |
| 280 | 3,360 | 3,584 | 6,720 | 7,168 | 13,440 | 14,336 |
| 300 | 3,600 | 3,840 | 7,200 | 7,680 | 14,400 | 15,360 |
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.
Rated versus usable energy
The result is the battery's rated energy. You get less in practice because:
- Depth of discharge: lead-acid batteries are commonly kept above 50% charge to protect their life, while LiFePO4 batteries are often used to 80–100% of capacity.
- Inverter losses: converting battery DC to household AC typically loses about 5–15%.
- Discharge rate: lead-acid capacity is usually quoted at a slow 20-hour rate; drawing current faster yields fewer amp-hours (the Peukert effect).
How long will the battery run my device?
Runtime in hours ≈ usable Wh ÷ device watts. A 1,280 Wh LiFePO4 battery with 90% usable capacity and a 90%-efficient inverter running a 100 W load lasts roughly 1,280 × 0.9 × 0.9 ÷ 100 = 10.4 hours.