Battery Life Calculator
Estimate how long a battery will last from its capacity (mAh or Ah) and the device’s current draw.
Enter your values and press Calculate.
How to use the Battery Life calculator
Real capacity drops in cold weather and at high discharge rates.
Formula
Hours = capacity (mAh) × usable fraction ÷ load (mA)
More electrical calculators
Ohm's Law CalculatorVoltage, current, resistance and power from any two values.Watts to Amps CalculatorCurrent draw from power and voltage (AC and DC).Amps to Watts CalculatorPower from current and voltage (AC and DC).Electricity Cost CalculatorRunning cost of any appliance per day, month and year.Voltage Drop CalculatorVoltage drop along a cable run.kVA to Amps CalculatorCurrent from kVA for single and three phase.Horsepower to Amps CalculatorMotor current from horsepower.Resistor Colour Code CalculatorResistance from 4-band colour codes.Series & Parallel Resistor CalculatorTotal resistance of resistors in series or parallel.