UntilOff tells you how long you can use your phone until it has to be charged again based on your prior usage.
Other apps tell you how long you can use the 3G or browse the internet with the residual battery. UntilOff tells you how long you can use your phone as you used it before.
To achieve this UntilOff takes measurements of your battery level every time you start it. In addition you can activate geo fences to measure the battery level automatically when you leave home or your work.
Start UntilOff after you have charged your phone and every time you need to know the residual battery duration.
In addition UntilOff saves the prediction of the total battery duration. After a while youll therefore have the distribution of your total battery duration.
About battery usage:
Continued use of GPS running in the background can dramatically decrease battery life. UntilOff uses geo fences. Those work mostly using WiFi and cell tower signals for location.