The fretboard below show the notes for a Standard Guitar when "Cross-note C" is used. The strings are tuned to the following notes:
C2G2C3G3C4D♯4
For other alternatives see the available tunings for Standard 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