Bdim Guitar Chord

Bdim is the B diminished chord, a diminished triad. It has three notes: B, D and F. It is the diminished chord guitarists meet first, because it is the seventh chord of the key of C major. The standard shape starts at the 2nd fret and uses four fingers with no barre.

Root on the A string at fret 2, four fingers in a diamond, no barre. The same grip plays any diminished chord if you move the root.

How to play Bdim, step by step

Index finger: 2nd fret, A string
Middle finger: 3rd fret, D string
Ring finger: 3rd fret, B string
Pinky finger: 4th fret, G string
Strum from the A string down, skipping the low E. The high E string stays muted; let the nearest fretting finger touch it lightly.

Nothing here rings open, so the whole grip slides: one fret up it is Cdim, two frets down it is Adim on the A string root.

More ways to play Bdim

There are 2 common Bdim shapes in total: the standard one at the top of the page, plus these, easiest first. You only ever need one. Tap any card to hear it.

Bdim guitar chord diagram, compact, frets 9 to 12, played x x 9 10 12 10 — Compact, frets 9 to 12

If it buzzes or goes quiet

The D note on the B string dies: The pinky, reaching over to the G string, is resting on the B string underneath it. Curl the pinky so it stands on its tip.
Stray open strings ring: Neither E string belongs in this chord. Tip of the index mutes the low E; the pad of the ring finger quiets the high E. Aim your strum at the middle four strings.
Notes buzz even when everything is fretted: Fingers 2, 3 and 4 sit in a tight diagonal and pull each other flat. Keep each finger on its very tip, close behind the fret wire, and check one string at a time.

What makes it a Bdim

B · D · F 1 ♭3 ♭5

Bdim is B, D and F: two minor thirds stacked. Compared with B minor, the fifth has dropped from F♯ to F, and that flat fifth removes all the stability. The chord sounds like a question that needs an answer, and the answer is C: B pulls up to C, F pulls down to E, and you land on a C major chord.

This is why Bdim matters more than most diminished chords. Build a chord on every note of the C major scale and six come out major or minor; the one built on B comes out diminished. It works as the vii chord of C major and the ii chord of A minor. Bdim is also G7 with the G removed (G7 is G, B, D, F), which is why the two chords resolve to C the same way.

Bdim vs Bm

One note separates them: Bm is B, D, F♯ and Bdim lowers that F♯ to F. The feel could not be more different. Bm is a stable chord songs can live on; Bdim is pure tension that wants to move to C. The shapes are cousins on guitar: in the common Bm barre at the 2nd fret the D string plays F♯ at the 4th fret, and dropping that note one fret while losing the barre gives you the Bdim grip. If you are playing in C major or A minor and the chart says B something, check the symbol: B° means this chord, not the minor.

Bdim chord questions

Is Bdim hard to play?

It takes four fingers packed into three frets, but no barre. Most players find it easier than the Bm barre chord once the pinky learns to arch.

What is the difference between Bdim and Bdim7?

Bdim is the triad: B, D, F. Bdim7 adds A♭ as a fourth note. When a chord chart writes Bdim or B° with no 7, it means the three note chord on this page. There is also Bm7♭5, which adds A instead of A♭; that one is common in jazz.

Why is Bdim the diminished chord of C major?

The C major scale has no sharps or flats, and stacking scale notes on top of B gives B, D, F: a diminished triad. Every major key has exactly one diminished chord, built on its seventh note.

What does Bdim resolve to?

C major, one half step up, or A minor when it acts as that key's ii chord. It shares three notes with G7, so it resolves anywhere G7 does.

Can I play Bm instead of Bdim?

Not in the key of C, where the F natural is the point of the chord. Substituting Bm brings in F♯, a note outside the key, and the pull toward C disappears.