kWh = Voltage × Ah ÷ 1,000 — with a quick reference table for common LiFePO4 battery sizes.
Battery capacity is usually quoted in amp-hours (Ah), but the energy a battery actually stores is measured in kilowatt-hours (kWh). This calculator converts Ah to kWh in seconds — enter the battery’s nominal voltage and capacity below, or use the formula and reference table further down.
kWh = Voltage × Ah ÷ 1,000. Usable energy is lower once depth of discharge and system losses are applied.
The formula is simple:
kWh = Voltage (V) × Capacity (Ah) ÷ 1,000
Why divide by 1,000? Because volts × amps = watts, and watts × hours = watt-hours, and 1,000 watt-hours equals one kilowatt-hour. A 12.8V 100Ah battery therefore stores 12.8 × 100 = 1,280Wh = 1.28kWh.
One caveat when comparing batteries: use the nominal voltage (12.8V for a “12V” LiFePO4 battery, 25.6V for “24V”, 51.2V for a “48V-class” system), not the charger or peak voltage — otherwise the result is off.
| Battery | Nominal energy |
|---|---|
| 12.8V 50Ah | 0.64kWh |
| 12.8V 100Ah | 1.28kWh |
| 12.8V 200Ah | 2.56kWh |
| 12.8V 300Ah | 3.84kWh |
| 25.6V 100Ah | 2.56kWh |
| 48V 100Ah | 4.8kWh |
| 51.2V 100Ah | 5.12kWh |
These figures are nominal energy at full rated capacity. Usable energy is lower once depth of discharge, temperature and system losses are applied — our battery bank sizing guide walks through the full calculation.
Two batteries with the same Ah rating can store very different amounts of energy if their voltages differ: a 48V 100Ah pack holds 4.8kWh — almost four times the 1.28kWh of a 12.8V 100Ah pack. For procurement, comparing quotes on price per kWh rather than price per Ah is the fair way to evaluate batteries and suppliers.
Need a specific capacity for an upcoming project? Send us the energy target and destination — we will confirm the closest standard configuration and quote it.
It depends on the voltage: a 100Ah battery stores 1.28kWh at 12.8V, 2.56kWh at 25.6V, 4.8kWh at 48V and 5.12kWh at 51.2V. Use kWh = V × Ah ÷ 1,000 to convert any battery, and always check the nominal voltage before comparing models.
No. Ah measures charge capacity, while kWh measures energy. The two are linked by voltage — which is why the same 100Ah rating can mean 1.28kWh or 5.12kWh depending on the battery’s voltage. For storage and backup projects, kWh is the number that compares directly with your daily consumption in kilowatt-hours.
The formula gives nominal energy. Usable energy is reduced by depth of discharge, temperature, discharge rate, inverter losses and the end-of-life capacity threshold. Plan with a margin: many daily-use systems draw up to 80% of nominal energy, and less in cold conditions.
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