How to Calculate Battery Runtime?

How to Calculate Battery Runtime
3 mins read

Batteries power everything in today’s technologically advanced society, including our smartphones and electric cars. To make sure that our devices survive as long as possible without losing power at important times, it is imperative to understand battery runtime.

How would you know your mobile battery would run for hours?


Typically, many of us would know by experience itself. We charge our mobile phone completely and then we see for several hours after which the battery demanded charging again.

However, this usually misleads us.

To avoid that, we have made this calculator to estimate your battery runtime. Also, we’ll look at the variables that impact battery runtime and give you a step-by-step tutorial on how to calculate battery runtime precisely.

Battery Runtime Calculator

How to use the calculator?

  • For this calculator, enter the battery capacity in mAh.
  • Know the device consumption and enter the value in mA.
  • Enter the consumption rate. If you do not know the consumption rate, enter the value as ‘0.7’.
  • The calculator would show automatically the calculated value.

How to calculate Battery Runtime?

Now, let us take a look at how to calculate the battery runtime and what are the variables that you should consider to calculate it accurately.

Battery Capacity

Battery capacity is the total charge that a battery can hold. It is typically expressed in milliampere-hours (mAh) or watt-hours (Wh). Given that a larger capacity equates to more energy storage and, thus, a longer runtime, it is an important component in determining battery runtime.

Look for the information printed directly on the battery itself or consult the manufacturer’s specs to determine the battery capacity. Remember that the capacity of various battery chemistries varies, so be careful to consider this variance.

Battery runtime

Battery runtime is directly influenced by a device’s power usage. The battery depletes more quickly the higher the power consumption. The units of power consumption are commonly watts (W) or milliwatts (mW).

You can look at a device’s manufacturer-provided specifications to find out how much power it uses. Look for details such as the amount of power used while in various modes (standby, active, etc.), or refer to the user manual. To evaluate power use precisely, you might occasionally need to utilize a power meter or specialized software.

Battery Runtime Calculation formula

When you know the battery capacity and power consumption values, the formula to calculate battery runtime is simple to use.

Battery runtime = (Battery capacity in mAh / Load current consumption in mA) X Consumption rate

Example: Let us say you have a 10000 mAh battery. The load is drawing a 500 mA current. The battery life would be 14 hours considering the consumption rate as 0.7.

Make sure the units are accurate. For instance, the result will be in hours if the battery capacity is supplied in mAh and the power usage is specified in mA. The output will be in hours if the battery capacity is specified in Wh and the power usage in W.

Do Not forget to consider the Conversion factor

Batteries’ conversion factor (efficiency) at converting stored energy into productive work in practical situations varies. The total runtime is shortened due to energy loss from heat or other causes. You can adjust the calculation by adding an efficiency factor to account for this.

(Battery Capacity / Power Consumption) * Conversion Factor (Efficiency) = Runtime

A common efficiency factor runs from 0 to 1, with 1 denoting complete efficiency. The efficiency factor may change depending on the exact battery chemistry and the device. An efficiency factor between 0.7 and 0.9 is often acceptable for the majority of consumer electronics.

Consider Other Factors

Even though the equations above give a reasonable idea of battery runtime, it’s crucial to keep in mind that other factors can affect it. Temperature, battery age, device settings, software optimization, and the existence of background programs are some of these variables. Extreme temperatures and taxing workloads typically reduce battery life, although efficient software and settings can increase it.


A useful ability that enables users to successfully plan their device usage and guarantee they have adequate power when needed is calculating battery runtime. You can precisely estimate runtime by comprehending battery capacity, power use, and accounting for efficiency. Remember to take into account any extra elements that could impact battery performance in practical applications. With this information at hand, you can make wise choices to extend battery life and improve your entire device experience.



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