Open G and Open D Tuning

An open tuning turns the guitar's open strings into a complete chord: strum with no fingers down and you get a full major chord, not a suspended wash or a stack of fourths. That single property is why open tunings own slide guitar and a huge slice of blues — a straight barre (or a slide laid straight across) at any fret is a whole chord, in tune, everywhere on the neck. Open G and Open D are the two you'll meet most, and they're similar enough to cover in one sitting.

Open G: D-G-D-G-B-D

Three strings move from standard, all down a whole step, and the middle three don't move at all:

| String | Standard | Open G | Change | | ------ | -------- | ------ | ------ | | 6th (lowest) | E2 · 82.41 Hz | D2 · 73.42 Hz | down a whole step | | 5th | A2 · 110 Hz | G2 · 98 Hz | down a whole step | | 4th | D3 · 146.83 Hz | D3 · 146.83 Hz | unchanged | | 3rd | G3 · 196 Hz | G3 · 196 Hz | unchanged | | 2nd | B3 · 246.94 Hz | B3 · 246.94 Hz | unchanged | | 1st (highest) | E4 · 329.63 Hz | D4 · 293.66 Hz | down a whole step |

The open strings spell G major (G-B-D, with the G chord's fifth on the bottom). This is the tuning of Delta blues slide playing and — through Keith Richards, who built a career's worth of Rolling Stones riffs in it — of a whole school of rock rhythm guitar. Richards famously removes the low 6th string entirely so the open G root is the lowest note; with all six strings, many players simply avoid the bottom D when they want a clean G chord.

Open D: D-A-D-F#-A-D

Open D moves four strings, and one of them is the trap. Three drop a whole step — the same outer-string moves as DADGAD — but the 3rd string drops only a half step, from G to F#:

| String | Standard | Open D | Change | | ------ | -------- | ------ | ------ | | 6th (lowest) | E2 · 82.41 Hz | D2 · 73.42 Hz | down a whole step | | 5th | A2 · 110 Hz | A2 · 110 Hz | unchanged | | 4th | D3 · 146.83 Hz | D3 · 146.83 Hz | unchanged | | 3rd | G3 · 196 Hz | F#3 · 185 Hz | down a HALF step | | 2nd | B3 · 246.94 Hz | A3 · 220 Hz | down a whole step | | 1st (highest) | E4 · 329.63 Hz | D4 · 293.66 Hz | down a whole step |

That F# is the chord's major third — the note that makes the open strum D major rather than a bare drone — and it's the one to tune carefully. A half step is a short trip, and if you turn the peg at whole-step speed you'll sail past F# toward F. Watch the tuner closely on this string: go down slowly, stop when the display re-labels the pitch F#, and center it in the Tuned band. Overshooting to F turns your bright D major into D minor's darker cousin and everything strummed sounds subtly wrong.

Open D is the other great slide tuning — Elmore James' "Dust My Broom" lick lives here — and a staple of folk and lap-style playing.

Playing them

In both tunings the payoff is the same: the open strum is the chord, and a barre or slide across all six strings at any fret is another major chord. Fret 5 gives you the IV chord, fret 7 the V — the whole I-IV-V of a blues sits under one finger. For slide, the tuning does the harmonic work while the slide handles pitch and vibrato; keep the slide directly over the fret wire, touch the strings lightly (don't press to the fingerboard), and let the tuner confirm your open strings are true before you blame your slide technique.

The caveat: uneven tension

Both tunings slacken several strings — and in Open D, by different amounts on neighboring strings. That asymmetry has real consequences. The loosened strings flap wider, buzz more easily, and drift sharp under a heavy strumming hand or a firmly pressed slide. The changed total pull also lets the neck relax slightly, which can nudge even the unchanged strings. So: retune the whole guitar a few minutes after arriving in the tuning, expect the slack strings to need more frequent touch-ups than you're used to, and if you live in open tunings, consider a heavier string set — extra gauge on the strings that drop restores some of the lost tension.

Getting back to standard is the reverse trip; the exact targets are in the Standard Tuning Reference. And if you like retuned guitars but want modal ambiguity instead of a committed major chord, that's DADGAD — one string away from Open D.