The fretboard below show the notes for a Ukulele (Concert) when "Open C" is used. The strings are tuned to the following notes:
G3C4E4G4
For other alternatives see the available tunings for Ukulele (Concert)
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