# How long can the Mobile 25600 power my laptop?Updated a year ago

This question involves some complexity due to the variable power consumption of your laptop, depending on whether you're gaming or simply browsing the internet. This variability impacts the time and percentage of charge that Omnicharge can provide to your laptop.

We adopt a more objective approach to simplify matters by comparing Omnicharge's battery capacity to the laptop's internal battery. This also takes into account the the efficiency loss of Omnicharge's conversion circuits. The equation for calculating the charge percentage is as follows:

**Charge Percentage = (Omnicharge's Battery Capacity / Laptop's Internal Battery Capacity) * (Omnicharge's Conversion Circuits Efficiency)**

For instance, let's consider the Omni Mobile 25600 and the 15'' MacBook Pro (2019 model). The Omni Omni Mobile 25600 has a battery capacity of **92Wh**, and the 15'' MacBook Pro has an internal battery capacity of **83.6Wh.** The Omnicharges conversion efficiency is around 90%. Plugging in these values into the equation yields:

**92Wh / 83.6Wh * 90% = 0.99**

This means that the Omnicharge can charge the 15'' MBP around **1 time**, effectively doubling your laptop battery life. This is assuming that the laptop is turned off or in sleep mode. Operating the laptop while charging will impact this calculation. The equation will be the same for both the DC output and the USB-C output, as these have similar conversion efficiencies.

Remember that you might get significantly different results in real life. Let's say that your laptop battery is already fully charged, and you are only using the Omnicharge to extend the battery life. Since the laptop battery is already full, the power draw will be significantly lower, which also means that the Omnicharge will output less heat and will, therefore, have higher efficiency.