This learning and free compass app explains everything you need to know about compasses Variation, deviation and gyro error are clearly explained in the theoretical section and practically applied in the calculator section. You can calculate heading relations in two directions: from compass to map and from map to compass.
The download of the app doesn't contain viruses or any kind of malware. Compass Calculator is created by DBG Nautical and its category is Educational. The tool was rated 4.5 on Google Play.
Over 50K users downloaded and installed this application and the most recent release was on Sep 18, 2020. It's free to download the installer of Compass Calculator, also, you can have a look at users' reviews on Droid Informer. The app runs on Android 4.0 and higher.