This compass is a tool to search bearings(azimuth) using the built-in magnetic sensors.
The compass app depends on the performance of your device EXACTLY.
If it works perfectly, this means your sensors are perfect, too.
If it is inaccurate, please check that you aren't being affected by a magnetic field and the sensors become weakened by age.
In order to calibrate your device, there are several options.
Professional Compass for Android.
Simple and powerful tool in your pocket
Mini Compass is the compass in your pocket, when you need it, where you need it.
Motorola DroidX Compass
Samsung Galaxy S Compass
Samsung Galaxy Note Compass
Samsung GT Compass
Samsung Galaxy Ace Compass
Samsung Galaxy Mini Compass
Samsung Galaxy Gio Compass
Motorola Droid2 Compass
Samsung Fascinate Compass
Samsung Epic 4G Compass
Motorola Droid Compass
Motorola Defy Compass
T-Mobile G2 Compass
LG Optimus Compass
LG Ally Compass