Bdim guitar chord
An open string left ringing against a fretted grip. Because it costs no finger, it sounds a note the closed shape has none left for -- a tension on top, or a pedal root underneath. Either a familiar grip with open strings added, or a shape so sparse the open strings carry the chord. These belong to their key rather than to a shape, so D, A, G and E have many and Eb a handful.
- Tap a note to hear it
- Arrows change position
- Fingers, notes or intervals
- Play the chord
About Bdim — open string voicings
Bdim is B, D and F — Bm with the fifth lowered as well.
It sounds compressed and unstable in every direction. Rarely a destination; it is where a line passes through on the way somewhere.
Bdim notes and formula
| B | D | F |
|---|---|---|
| 1 | ♭3 | ♭5 |
Unstable — it does not sit still.
Also written B°, Bo or B diminished. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play Bdim
An open string left ringing against a fretted grip. It costs no finger, so it can sound a note the closed shape has none left for: a tension on top, or a pedal root underneath.
These belong to their key rather than to a shape: they cannot be moved up the neck. D, A, G and E have many; E♭ has a handful.
Bdim has 6 of them, on strings 5-4-3-2-1, strings 6-4-3-2-1 and the top four strings, from the 2nd fret up to the 6th — every inversion the chord has: B in the bass and D in the bass. The one to learn first is the B shape at the 2nd fret, which is the easiest grip here.
3 of them sit on strings 5-4-3-2-1, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with x20x01 — 2 open strings and only 2 fretted notes. 1 of the 5 shapes here sits in open position. None of them needs a barre. Together they cover the neck from the 1st fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x20x01 | open position | B, root position | F | 2 open strings |
| x2343x | 2nd fret | B, root position | D | all fretted |
| 75x76x | 5th fret | B, root position | F | all fretted |
| x-x-9-10-x-10 | 9th fret | B, root position | D | all fretted |
| x-14-12-x-12-13 | 12th fret | B, root position | F | all fretted |
The same notes rebuilt from scratch give 48 triad voicings, each on its own page.
Tensions. A shell of Bdim, root, third and seventh, leaves a string free, and the tones that belong over it are the 11 (E) and the b13 (G).
How to use Bdim
In which keys. Every note of Bdim belongs to C major (the vii°, the leading tone) and A minor (the ii°, the supertonic).
What to play over Bdim
Every note of Bdim is in B blues, B locrian, B altered, B diminished and B half-whole diminished.
Chords near Bdim
Change one note of Bdim and you have Bm (the flat fifth becomes a fifth), Bdim7 (add the sixth), Bm7b5 (add the flat seventh) or BmMaj7b5 (add the major seventh).
Bdim is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
On Bdim’s sound and use this page follows Stefan Kostka, Dorothy Payne & Byron Almén, Tonal Harmony (McGraw-Hill, 8th ed., 2018). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.