How often can I charge my phone with a Power Bank?

Are you looking to determine how many times you can charge your phone using a Power Bank? Understanding this calculation can help you plan your power usage and ensure that your devices stay charged on the go. In this guide, we'll walk you through the process of calculating the number of phone charges using a simple formula.

The Formula:

(Number of Phone Charges) = (Power Bank Capacity in mAh × 0.85) / Phone Battery Capacity in mAh

Do you want to know the charging times of other devices like your laptop. In our blog “How to calculate the number of device charges using a Power Bank or Power Station” we explain how!

Step-by-Step Instructions:

1. Gather the Necessary Information

Before you start calculating, make sure you have the following information:

  • The capacity of your Power Bank in Milliampere-Hours (mAh). This information can usually be found on the product packaging, user manual or online.

  • The capacity of your phone battery in Milliampere-Hours (mAh). This information can often be found on the device itself, in its specifications or online.

2. Understand the Variables

  • Milliampere-Hours (mAh): This measurement represents the amount of electrical charge a battery can hold and deliver. Milliampere-hours (mAh) is a unit that combines current, measured in milliamperes, with time, measured in hours, to indicate the capacity of a battery. It signifies the quantity of charge the battery can provide over a specific duration before requiring recharging.

  • The 0.85 factor used in the formula accounts for various energy losses and inefficiencies that occur during the process of charging a device with a Power Bank.

3. Plug in the Values

Now that you have the required data, you can use the formula to calculate the number of device charges. Plug in the values:

(Number of Device Charges) = (Power Bank Capacity × 0.85) / Device Battery Capacity

Multiply the Power Bank Capacity by 0.85 and then divide the result by the Device Battery Capacity. This will give you the approximate number of times you can charge your device with the power bank.


Let's say you have a Power Bank with a capacity of 10.000 mAh and a phone with a battery capacity of 4.000 mAh.

(Number of Device Charges) = (10.000 mAh × 0.85) / 4.000 mAh

(Number of Device Charges) = 8.500 mAh / 4.000 mAh

(Number of Device Charges) ≈ 2,13

In this example, the power bank can approximately charge the phone 2.13 times.

Essential Power Bank

Additional tips

  • Charging experiences may differ from theoretical calculations due to factors like temperature, battery health and power source quality.
  • Devices may consume varying amounts of power based on their usage, settings and features being used.
  • If you plan to charge multiple phones, sum up their individual capacity in mAh and factor that total into your calculations.

Calculating the number of device charges using this formula can help you make informed decisions about how to best utilize your Power Bank and keep your devices powered up while on the move.

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