Bdim7 is a diminished 7th chord, and on the guitar it is played from the notes B, D, F, G#. Its first guitar voicing is the open position: low E string muted; A string at fret 2 (ring finger); D string open; G string at fret 1 (index finger); B string open; high e string at fret 1 (middle finger). This page is a complete reference for it: notes and intervals, fingerings, mistakes to avoid, the keys it belongs to and a short practice routine.
What notes are in the Bdim7 chord?
The Bdim7 chord is a diminished 7th chord, and its notes are fixed: B, D, F, G#. Every voicing on every instrument uses these same notes, in some order and in some octave — change one of them and you are playing a different chord. The table below lists each note with its interval from the root B, so you can see the structure of Bdim7 at a glance. On the guitar, the open position voicing is the place to hear it in Bdim7.
| Note | Interval |
|---|---|
| B | Root |
| D | b3 |
| F | b5 |
| G# | 6 |
The root is B, the note the chord is named after and the note your ear hears as home. Above it, the intervals in Bdim7 are b3, b5, 6. Those intervals are the fingerprint of the diminished 7th quality — any chord with the same interval pattern, on any root, is the same kind of chord. On the guitar, the notes appear in the order the fingering dictates, but the set of notes never changes.
Bdim7 sounds tense, dark and symmetrical — the diminished 7th chord divides the octave into four equal parts and sounds like it belongs nowhere. Listen for that character when you play it — if Bdim7 does not sound that way, one of the notes is probably wrong, and the table above is the place to check. On the guitar, the open position voicing is the place to hear it in Bdim7.
Comparing Bdim7 with its closest relatives helps to fix it in your ear. In short, diminished 7th against half-diminished: Bdim7 flattens the 7th twice, to G#; the half-diminished chord keeps the flattened 7th A. That one note changes the whole character. Practise the two chords back to back and listen to the one note that changes — that single note is the difference between the two chords. On the guitar, the open position voicing is the place to hear it in Bdim7.
How to play Bdim7 on guitar
On the guitar, Bdim7 has 3 voicings in the data below, and each one uses the same notes — B, D, F, G# — in a different place on the neck. The first voicing below is the one to learn first, and the alternatives cover the rest of the neck. Finger numbers below use 1 for the index finger, 2 for the middle finger, 3 for the ring finger and 4 for the little finger, and x means the string is not played.
The open position puts Bdim7 in open position: low E string muted; A string at fret 2 (ring finger); D string open; G string at fret 1 (index finger); B string open; high e string at fret 1 (middle finger). The challenge here is the muted string: 1 string is marked x, and it needs to stay silent. Let the edge of a fretting finger rest lightly on it — muting by touch, not by pressing. Strum or pluck it slowly first and check that every note in Bdim7 — B, D, F, G# — sounds, with no buzz and no accidental open string.
Another way to play Bdim7 is the barre chord, in open position: low E string at fret 1 (index finger); A string at fret 2 (middle finger); D string at fret 3 (ring finger); G string at fret 1 (index finger); B string at fret 3 (little finger); high e string at fret 1 (index finger). It barres across strings 1 to 6 at fret 1 with the index finger. The barre is the hard part: the index finger must press every string from 1 to 6 evenly at fret 1, so roll it slightly onto its bony side and keep it close to the fret wire. If the barre buzzes, move it a fraction closer to the fret and press from the arm, not the thumb alone. Strum or pluck it slowly first and check that every note in Bdim7 — B, D, F, G# — sounds, with no buzz and no accidental open string.
The movable voicing is the voicing to learn if you want Bdim7 in around fret 4: low E string at fret 7 (little finger); A string at fret 5 (ring finger); D string open; G string at fret 4 (index finger); B string at fret 6 (little finger); high e string at fret 4 (middle finger). The stretch is the challenge: the fretted notes span from fret 4 to fret 7, so keep your thumb low behind the neck and let your fingers reach rather than squeezing the neck. Strum or pluck it slowly first and check that every note in Bdim7 — B, D, F, G# — sounds, with no buzz and no accidental open string.
Choosing between the voicings of Bdim7 is a musical decision, not a right-or-wrong one. The open or low-position voicing rings the most and suits strumming, while a barre or movable voicing lets you slide Bdim7 up the neck to any key without changing the shape. When you change chords, pick the voicing of Bdim7 that sits closest to the chord before it — shorter moves between shapes mean faster, cleaner changes. Practise the change into Bdim7 from the chord that comes before it in your song, not the chord on its own, because the move is the skill. On the guitar, the open position voicing is the place to hear it in Bdim7.
A short practice routine for Bdim7 on the guitar: play the first voicing four times slowly, checking each note, then change to it from the chord a fourth above B and back, four times, at a slow tempo. Then play the second voicing the same way. If a note buzzes, stop and fix the finger placement rather than playing through the buzz — clean notes at a slow tempo become clean notes at full tempo, while buzzes practised fast become habits. Use the Guitar Chord Finder to see the diagram for Bdim7 while you practise, and the Chord Finder to compare it with the same chord on other instruments.
Common mistakes
These are the mistakes that most often make Bdim7 sound wrong on the guitar, and each one has a concrete fix. Work through them one at a time rather than trying to fix everything at once.
Using it as a home chord. Bdim7 is unstable by design. It is a passing chord and a dominant substitute, not a tonic. On the guitar, the open position of Bdim7 puts those notes under your fingers in the order the fingering lists them.
Voicing it too low. Four notes a minor 3rd apart sound muddy in low octaves. Spread them out or use a higher voicing. On the guitar, the open position voicing is the place to hear it in Bdim7.
Forgetting it is symmetrical. Because the notes are evenly spaced, Bdim7 can resolve in four directions. Practise resolving it to the tonic and to the chord a semitone above its root. On the guitar, start with the first voicing above and listen for the notes B, D, F, G# in Bdim7.
Barre collapsing on the high strings. In a barre voicing of Bdim7, the high strings are the ones that buzz first, because the index finger presses hardest near the thumb. If the top notes of Bdim7 sound dead, roll the barring finger slightly toward the fret and press from the arm, not from squeezing the neck. On the guitar, the open position voicing is the place to hear it in Bdim7.
Where Bdim7 is used
Bdim7 is not a diatonic triad in any major or minor key, because it is an extended or altered chord, but its base triad belongs to the key of D major, the key of G major, the key of A major. a passing chord and a dominant substitute: it can resolve to several different tonics. As a dominant-type chord it also points toward E major, the key a perfect fourth above B, which is the tonic it most often resolves to. That is where Bdim7 does its work: not as a home chord, but as a chord that creates movement and then resolves. On the guitar, the open position voicing is the place to hear it in Bdim7.
Because Bdim7 is an extended or altered chord, it appears in progressions as a colour or a dominant rather than as a diatonic staple. Try it in place of the plain B triad in a progression you already know, and listen to how the extra notes change the feel — that substitution is the usual way extended chords enter real music. The Chord Progression Builder lets you try Bdim7 in a progression in any key and hear how it connects to the chords around it. On the guitar, start with the first voicing above and listen for the notes B, D, F, G# in Bdim7.
The same chord on other instruments is covered in Bdim7 on piano, Bdim7 on ukulele, Bdim7 on bass, and the scales that fit over it are the B major scale and the B minor pentatonic scale. Learning Bdim7 on the guitar and then checking it on another instrument is one of the best ways to fix the notes — B, D, F, G# — in your memory, because the notes stay the same while everything else changes.
Practising Bdim7
A short worked example makes Bdim7 concrete. Play the four-chord progression E – B – C#m – A in E major, the key Bdim7 most often resolves toward: E – B – C#m – A. Play each chord for one bar at a slow tempo, and listen to how Bdim7 sounds in that sequence — whether it feels like home, like a lift, or like a chord on its way somewhere else. Then play the same four chords in a different order, starting on Bdim7 itself, and notice how its character changes when it opens the progression instead of sitting inside it. On the guitar, the open position voicing is the place to hear it in Bdim7.
For a second exercise, play Bdim7 and then the chord a fourth above B, back and forth, four times each. That move — a chord and the chord a fourth above it — is the most common resolution in Western music, and it is the move Bdim7 is built for when it acts as a dominant. Finish by playing Bdim7 on its own, slowly, and naming each note out loud as you play it: B, D, F, G#. Naming the notes while you play them is what turns a shape into knowledge you can use in any key. Test yourself with the Practice Chord Quiz and keep time with the Metronome as the tempo rises. On the guitar, the open position of Bdim7 puts those notes under your fingers in the order the fingering lists them.
Frequently asked questions
Why does Bdim7 sound so tense?
Every interval in it is a minor 3rd, and the chord contains two tritones. There is no stable note to rest on, so the ear hears it as a chord that must move. On the guitar, the first voicing above shows where that note sits.
Where is Bdim7 used?
As a passing chord between two chords a whole step apart, as a dominant substitute, and as the vii°7 chord in harmonic minor. It is a brief, dramatic colour, not a chord to sit on. On the guitar, the first voicing above shows where that note sits.
How do you play Bdim7 on the guitar?
The first voicing is the open position: frets x–2–0–1–0–1, fingers 0–3–0–1–0–2, on the guitar. That voicing uses the notes B, D, F, G#, and it is the one to learn first. The page above lists more voicings for Bdim7, so you can choose the shape nearest the chords around it.
Is Bdim7 hard to play on the guitar?
It depends on the voicing. The first voicing of Bdim7 on the guitar is the easiest starting point, and the movable voicings further up the neck are harder because they need a barre or a wider stretch. Practise the first voicing cleanly at a slow tempo before you try the others, and the harder shapes will come more easily.
What is the easiest voicing of Bdim7 on the guitar?
The open position is the easiest voicing listed for Bdim7 on the guitar: frets x–2–0–1–0–1, fingers 0–3–0–1–0–2. Learn that shape first, get every note ringing cleanly, and only then move on to the alternative voicings further up the neck.