The fretboard below show the notes for a 7-String Guitar when "Drop A" is used. The strings are tuned to the following notes:
A1E2A2D3G3B3E4
For other alternatives see the available tunings for 7-String Guitar
The tuner is fully chromatic but if you need a reference of a specific tuning when tuning by ear or if you want to tune any other instrument follow the steps in how to setup the guitar tuner for other instruments