Ah to kW Conversion Calculator separates energy from power, using voltage and runtime to find kWh or average kW, and reverse-sizes battery Ah with efficiency and usable capacity.

Enter battery capacity and nominal voltage.

Ah measures charge. Average power also needs voltage and runtime. Assumptions default to 80% usable capacity and 90% efficiency; adjust below.

Usable capacity and efficiency

Blank uses 80%; this is an adjustable assumption.

Blank uses 90%; enter 100% for no conversion loss.

Common Mistakes Quick tips
  • Trying to convert Ah to kW without both voltage and duration; power needs energy ÷ time.
  • Confusing energy with power: Ah × V = Wh (energy), not kW unless you divide by hours and by 1000.
  • Missing unit scaling: mAh → Ah (÷1000), minutes → hours (÷60), seconds → hours (÷3600), kW ↔ W (×/÷1000).
  • Assuming voltage stays constant; real battery voltage varies with load and state of charge.
When to Use This Calculator
  • Estimate average power from a battery given capacity, voltage, and discharge time.
  • Size a battery: compute required Ah to support a kW (or W) load for a target duration.
  • Compare systems at different nominal voltages (12 V, 24 V, 48 V, etc.).
Input Definitions
  • Battery Capacity — in Ah (or mAh); a measure of charge capacity.
  • Power — average output over the chosen time, in kW or W.
  • Voltage — nominal system voltage in V (or mV/kV).
  • Time — discharge duration in hours, minutes, or seconds.
  • Conversions — output kW = Ah × V × U × η ÷ (t × 1000); required Ah = kW × 1000 × t ÷ V ÷ U ÷ η; nominal Wh = Ah × V; average battery current = usable Ah ÷ hours. U and η are usable-capacity and efficiency fractions.

Ah to kW Formula

The formulas below include usable fraction U and conversion efficiency η as fractions between 0 and 1; use time in hours and voltage in volts. The calculator defaults to U = 0.8 and η = 0.9. Set both to 100% for an ideal conversion.

kWₒᵤₜ = (Ah × V × U × eta) / (1000 tₕ) Ah = (kWₒᵤₜ × 1000 × tₕ) / (V × U × eta)
  • Ah = amp-hours (capacity), V = volts, th = time in hours; 1 kW = 1000 W.
  • Energy: Wh = Ah × V; kWh = Wh ÷ 1000.
  • Average battery-side DC current over the period: A = Ah × U ÷ th; conversion efficiency affects output power.

How do you convert Ah to kW? Multiply Ah by volts, usable fraction and efficiency, then divide by hours and 1000: output kW = Ah × V × U × η ÷ (t × 1000). This is an energy-budget estimate, not a maximum power rating.

How do you convert kW to Ah? Required Ah = output kW × 1000 × hours ÷ V ÷ U ÷ η. Real battery and inverter limits require a separate check.

Ah to kW Conversion Table

Ah to kW (12 V, 1 h, 100% usable and efficiency)
Capacity (Ah) Power (kW)
10.012
20.024
50.060
100.120
150.180
200.240
250.300
300.360
400.480
500.600
600.720
750.900
800.960
1001.200
1251.500
1501.800
2002.400
2503.000
3003.600
4004.800
* Using: kW = (Ah × V) ÷ (t × 1000). Table assumes V = 12 V, t = 1 h, U = 1 and η = 1.

Example Problem

Convert 100 Ah at 24 V over 2 hours to kW with both optional fractions set to 100%.

Use the formula: kW = (Ah × V) ÷ (t × 1000).

kW = (100 × 24) ÷ (2 × 1000) = 1.2 kW