The Dyrt PRO memory usage/storage use can be found inside the app store when you look at the specs and details for the app itself. If you are loading maps, the size will vary depending on how many maps and the size of the map download. Please make sure to have sufficient storage available on your phone or you will not be able to save them properly for offline management.While you can delete maps while offline, you can not load/add more so please ensure you have all map needs executed before you leave on your trip.