Free Online Open D Guitar Tuner
Four strings down, one of them by a semitone. Each read against its target.
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Left to right: 6th string, the thickest, to 1st, the thinnest. Tune one string at a time.
Allow microphone access to begin
How to use this tuner
Click Start Tuning and allow microphone access. Play one open string at a time, and the tuner shows how sharp or flat you are from that string’s target in cents. Tap a string button to hear the note and lock the tuner to it.
The bar spans −50 to +50 cents. Zero is perfectly in tune. In string mode the value is the distance to the target string, not to the nearest chromatic note, so a string that is a long way off pins the needle at the edge until you get close.
The tuner reads against the nearest open string of Open D tuning (D2, A2, D3, F♯3, A3, D4), so the cents value is the distance to that string, not to the nearest chromatic note. Tap a string to hear its reference pitch and lock the tuner to it; tap again to release.
Guitar is already selected and no transposition is applied: guitar is written an octave above where it sounds, and the tuner shows the sounding octave. Changing the dropdown to another instrument turns string mode off; tapping a string turns it back on.
Default is A440. Tap + / − to match a recording or another instrument that cannot be adjusted.
Open D tuning is D2, A2, D3, F♯3, A3, D4. From standard, four strings move: the sixth down a whole step (E to D), the third down a semitone (G to F♯), the second down a whole step (B to A), and the first down a whole step (E to D). The open strings sound a D major chord. It is the other classic slide tuning beside open G, the tuning of much of Joni Mitchell’s early work and of Elmore James, and it is DADGAD with the third string lowered one more semitone, which is why players who use one usually use the other.
The G to F♯ move is the delicate one. A semitone is a short turn of the peg and it is easy to sail past F♯ and end up at F, at which point a chromatic tuner cheerfully reports F and the chord sounds minor. This page reads the third string against F♯3 from the start and shows the cents, so you see the needle approach centre from the right and stop there. Tap the F♯ button to hear the target if you want to match by ear as well. For the three whole-step drops, the same string-mode logic keeps the note name fixed as you tune down through the halfway point.
Ear checks after tuning: D2 against D3 and D3 against D4 should be clean octaves; A2 against A3 likewise; and the F♯3 against the fourth fret of the fourth string should be a unison. The major third, F♯, is the string most worth tuning a hair flat if you are playing a lot of open-position chords, because an equal-tempered major third sounds slightly sharp against a pure one, which is audible on a sustained open chord. Two or three cents flat on that one string is a common slide-player habit; the tuner will show it as −2 or −3, which is fine.
Open E is open D raised a whole step on every string (E B E G♯ B E), which puts more tension on the neck and is usually played with a lighter set; many players tune to open D and capo at the second fret instead, which this page supports directly. The lowered strings in open D buzz more readily than in standard, and a heavier sixth and second string help. Run a second tuning pass after all four strings have moved, because the neck relaxes slightly when the total tension drops and every string creeps sharp.
Frequently asked questions
What are the notes in open D tuning?
D2, A2, D3, F♯3, A3, D4. The sixth, second, and first strings drop a whole step from standard and the third string drops a semitone from G to F♯. Strummed open they sound a D major chord.
What is the difference between open D and DADGAD?
Only the third string. DADGAD keeps it at G, giving a suspended chord; open D lowers it to F♯, giving a major chord. Everything else is identical, so switching between them is one peg turn.
Is open D or open E better for slide?
They are the same shape a whole step apart. Open E is brighter and tighter but puts more tension on the neck. Most players tune to open D and use a capo at the second fret when they need E, which is what this page supports.
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