Open D tunes the guitar strings to the basic notes from the D Major Chord. The notes used are D (root) - F♯ (3rd) - A (5th).
To tune to open D from standard tuning:
- Tune the low E (6th) string one step down to D.
- Tune the G (3rd) string half a step down to F♯.
- Tune the B (2nd) one step down to A
- Tune the high E (1st) string one step down to D.
Open D is a popular tuning for blues, folk, and rock genres, and works well with acoustic and electric guitars.
Open tunings use the notes from a chord so that playing all open strings play a chord. Open tunings are popular for slide guitar since a full chord can easily be played on all the guitar strings on the same fret.