The free B4UDRIVE application estimates your blood alcohol content (BAC) by taking into account your weight, the number of drinks you've had and what you've been drinking based on the National Highway Traffic Safety Administration (NHTSA) standards. If the results reveal that you're best leaving the driving to someone else, touching an icon on the screen will assist you in contacting a taxi.
The B4UDRIVE app is in no way intended to be a guideline for how much you can drink and still legally drive or avoid being arrested. The best policy always is don't drink and drive.
If you decide to use the taxi suggesting feature, B4UDRIVE will attempt to use your iPhone's rough location to determine the preferred taxi company in your local area.