A 12 fret guitar can play from E2 to E5 in scientific pitch notation. A piano can play from A0 to C8. The lowest note E2 can be played by playing the 6th string open. The highest note E5 can be played by fretting the 1st string, 12th fret. Music for the guitar is written one octave higher on the staff than the note sounds. If a note is written for guitar where E2 is shown, this would be an E3 on the piano. If a note is written where E5 is shown, this would be an E6 on the piano. The guitar notes are written just on a treble staff rather than bass and treble to make it easier to read.