Amp Hour (Ah) to Kilowatt-Hour (kWh) Calculator
Enter battery capacity and voltage to convert amp-hours to energy in kWh. Optional fields help estimate usable energy after efficiency and depth-of-discharge limits.
Formula: kWh = (Ah × V) ÷ 1000
What is the Ah to kWh conversion?
Amp-hours (Ah) measure electric charge, while kilowatt-hours (kWh) measure energy. To estimate how much energy a battery stores, you need both amp-hours and voltage. This is why a 100Ah battery at 12V stores much less energy than a 100Ah battery at 48V.
The formula
The core conversion is simple:
kWh = (Ah × Voltage) ÷ 1000
- Ah = battery capacity in amp-hours
- Voltage = nominal battery voltage (V)
- 1000 = converts watt-hours (Wh) to kilowatt-hours (kWh)
If you want realistic usable energy, multiply by efficiency and depth-of-discharge:
Usable kWh = Nominal kWh × (Efficiency/100) × (DoD/100)
Quick examples
Example 1: 100Ah at 12V
100 × 12 = 1200Wh = 1.2kWh
Example 2: 200Ah at 24V
200 × 24 = 4800Wh = 4.8kWh
Example 3: 280Ah at 48V (with 90% efficiency and 80% DoD)
Nominal: 280 × 48 = 13,440Wh = 13.44kWh
Usable: 13.44 × 0.90 × 0.80 = 9.68kWh (approx.)
Why this calculator is useful
This battery capacity calculator helps you plan:
- Solar battery banks
- RV and van electrical systems
- Off-grid backup power
- Marine battery setups
- DIY energy storage projects
It also makes it easy to compare batteries with different voltages using one common energy unit.
Common mistakes when converting Ah to kWh
- Ignoring voltage: Ah alone is not energy.
- Using unrealistic DoD: Not all chemistries should be fully discharged.
- Skipping efficiency losses: Inverters, wiring, and controllers reduce usable energy.
- Confusing Ah and A: Amp-hours are capacity over time, not current draw at one moment.
Ah, Wh, and kWh at a glance
Ah (Amp-hour)
Charge capacity (how much current can flow over time).
Wh (Watt-hour)
Energy capacity at a given voltage: Wh = Ah × V.
kWh (Kilowatt-hour)
Large energy unit used for home and system planning: kWh = Wh ÷ 1000.
Frequently asked questions
Can I convert Ah to kWh without voltage?
No. Voltage is required because energy depends on both charge and voltage.
Is nominal voltage always exact?
No. Battery voltage changes with state of charge and load, so kWh is an estimate based on nominal voltage.
What efficiency should I use?
For many systems, 85% to 95% is a practical range depending on inverter quality and wiring losses.
Final takeaway
To convert amp-hours to kilowatt-hours, multiply Ah by voltage and divide by 1000. For real-world planning, include inverter/system efficiency and usable depth-of-discharge. Use the calculator above to get both nominal and usable battery energy instantly.