Home > Laptop Battery Help > How To Calculate Battery Life

How to Calculate Laptop Battery Run Time

You can calculate your laptop battery life by dividing the battery capacity (Watt-hours or Whr) from the power consumption of your laptop (watts).

Calculate Battery Life
Watt Hours / Watts = Battery Life (in hours)

Example: 60 Whr / 20 Watts = 3 Hours

Laptop Battery Life Calculator
Enter the Watt Hours and Watts to calculate your battery life in hours. If you don't know the Watts or Watt-Hours, use the formulas below.


Calculate Watt-Hours
Whr= Volts x mAh / 1000

Example: 14.8 Volts x 4060mAh / 1000 = 60.09 Watt-Hours (rounded up)

Calculate Milli-Amp Hours
mAh = Whr x 1000 / Volts

Example: 60.09 x 1000 / 14.8 = 4060 mAH (rounded down)

Will a higher mAh battery rating negatively affect my laptop?
No. A battery with a higher mAh rating will not damage your laptop or power charger. It just means the battery has will store more energy inside. We use only the highest rated lithium-ion laptop batteries. Each one is backed by a 2 year warranty and 30 day money back guarantee.