Battery Capacity Calculator

How is Battery Capacity Calculated?

To calculate battery capacity, you must know the value of two variables: voltage and stored energy. Then you can use this formula and plug the values into it to get the battery capacity:

• BC = battery capacity


• SE = stored energy (in watt-hours)


• V = voltage (in volts)

Understanding Your Results

After using this tool, you will get a single number as your result that is displayed in ampere hours, by default. This number reflects how long the battery can last when running a single amp current. When using ampere hours, if the current is two amps then the battery capacity would be half that number, three amps would make the battery capacity one third of that number, and so on.

You can change the unit of measurement to milliampere hours, when you do this the number itself changes but it is still equal to the original ampere hours value you initially saw.

How to Use the Battery Capacity Calculator

If you are trying to find out the battery capacity of something you are in the right place. You can use this tool by following these steps:

1. Enter the voltage of the battery, by default volts is the selected unit of measurement but this can be changed if needed.


2. Enter the total stored energy value, watt-hours is the default unit of measurement but you should change it if you know the value in another unit.


3. Hit the calculate button and get the battery capacity in ampere hours or milliampere hours in less than a second!

Calculation Example

You have a battery that is 12 volts. It has a stored energy value of 60 watt-hours. You can plug these numbers into the formula we provided above, or use our calculator to do the math for you.

We enter 12 into the voltage field and then we enter 60 into the stored energy field. After hitting calculate we get our battery capacity answer of 5 ampere hours, or 5,000 milliampere hours.