1. The Blackout Calculator is a free iOS app that helps users calculate the duration of a power outage based on the capacity of their backup battery or generator. The app takes into account the user's device power consumption and the capacity of the backup power source to provide an estimate of how long the device can remain powered on during a blackout.

2. The app is designed to be user-friendly, with a simple interface that allows users to input their device's power consumption and the capacity of their backup power source. The app then calculates the estimated runtime and displays it in a clear and easy-to-understand format.

3. The Blackout Calculator is a useful tool for anyone who relies on their mobile devices during power outages, as it can help them plan and prepare for extended periods without electricity. The app is available for free on the iOS App Store and can be downloaded and used by anyone with an iOS device.