Ah to kWh Calculator
Convert battery capacity from amp-hours (Ah) to kilowatt-hours (kWh) using voltage and optional efficiency.
What does Ah to kWh mean?
Amp-hours (Ah) and kilowatt-hours (kWh) both describe energy, but they do it in different ways. Ah tells you how much electric charge a battery can deliver over time. kWh tells you total usable energy, which is usually what people need for solar setups, backup systems, RV power planning, and home battery sizing.
Because Ah alone does not include voltage, you cannot compare batteries fairly until you convert to watt-hours (Wh) or kilowatt-hours (kWh). A 100Ah battery at 12V stores much less energy than a 100Ah battery at 48V.
Ah to kWh formula
To convert amp-hours to kilowatt-hours, use this formula:
kWh = (Ah × Volts) ÷ 1000
If you want a more realistic estimate, account for system efficiency (inverter losses, wiring losses, conversion losses):
kWh = (Ah × Volts × Efficiency) ÷ 1000
Where efficiency is entered as a decimal (for example, 90% = 0.90). In the calculator above, you can enter efficiency directly as a percentage.
Step-by-step example
Example 1: 12V 100Ah battery
- Capacity: 100Ah
- Voltage: 12V
- Energy in Wh = 100 × 12 = 1200Wh
- Energy in kWh = 1200 ÷ 1000 = 1.2kWh
Example 2: 48V 200Ah battery bank at 92% efficiency
- Raw energy = 200 × 48 = 9600Wh
- Adjusted energy = 9600 × 0.92 = 8832Wh
- kWh = 8832 ÷ 1000 = 8.832kWh
Quick reference values
- 50Ah @ 12V = 0.6kWh
- 100Ah @ 12V = 1.2kWh
- 100Ah @ 24V = 2.4kWh
- 100Ah @ 48V = 4.8kWh
- 200Ah @ 48V = 9.6kWh
Common use cases
Solar battery sizing
If your daily load is in kWh, converting battery Ah to kWh helps you quickly estimate how long your battery bank can run your appliances.
RV and van electrical planning
Many RV batteries are marketed in Ah, while appliances are rated in watts. Converting to kWh makes it easy to estimate runtime for refrigerators, lights, fans, and charging electronics.
UPS and backup power
Backup systems often require runtime calculations in watt-hours or kWh. This conversion helps you compare battery options and avoid under-sizing your system.
Mistakes to avoid
- Ignoring voltage: Ah without voltage is incomplete for energy comparisons.
- Ignoring losses: Real-world output is lower due to inverter and system inefficiency.
- Assuming 100% depth of discharge: Battery lifespan is usually better with partial discharge.
- Mixing AC and DC values: Appliance usage is often AC; battery storage is DC.
FAQ
Can I convert Ah to kWh without voltage?
No. You must know voltage to convert Ah into energy (Wh/kWh).
Is a higher Ah battery always better?
Not always. A higher Ah value at low voltage can still store less total energy than a lower Ah battery at higher voltage.
Why include efficiency?
Efficiency gives a practical estimate of usable energy after conversion and delivery losses. This is useful for realistic battery runtime planning.
Final takeaway
The fastest way to compare battery capacity is to convert everything to kWh. Use the calculator above: enter Ah, voltage, efficiency, and battery quantity to get a clear, realistic energy estimate for your solar setup, backup power system, or mobile electrical project.