Battery Capacity Calculator: Determine Ah, Wh, Runtime & Power Needs

Calculate Your Battery Capacity Requirements

The nominal voltage of your battery or electrical system.
The average current (in Amperes) your device or total load draws.
How many hours you want the device or system to run.

Our intuitive Battery Capacity Calculator helps you determine the Amp-hours (Ah) or Watt-hours (Wh) needed for your electrical projects. Easily calculate battery requirements based on voltage, current draw, and desired runtime. Perfect for off-grid systems, RVs, marine applications, and DIY electronics.

Formula:

The core relationships for battery capacity, power, and runtime are derived from basic electrical formulas:

  • Power (P) = Voltage (V) × Current (I)
  • Amp-hours (Ah) = Current (I) × Time (T)
  • Watt-hours (Wh) = Power (P) × Time (T) or Voltage (V) × Amp-hours (Ah)

Where:

  • P = Power in Watts (W)
  • V = Voltage in Volts (V)
  • I = Current in Amperes (A)
  • T = Time in Hours (h)
  • Ah = Amp-hours
  • Wh = Watt-hours

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