Diminished Chord Guitar

01 · THE TRIAD

What is a diminished triad?

A diminished triad stacks a minor third and another minor third. In Bdim, those notes are B, D and F. The tight sound comes from the diminished fifth between B and F. Adding another chord tone makes a different chord: a diminished triad does not automatically include a seventh.

Chord symbols vary by chart. This page uses “Bdim” and “B°” for the three-note triad. Some arrangements use “dim” as shorthand for dim7, so check the written notes or the arranger’s convention if the intended seventh is unclear.

02 · HALF DIMINISHED

Half diminished chord guitar

A half-diminished seventh chord uses 1, ♭3, ♭5 and ♭7. B half-diminished is B–D–F–A; it is written Bm7♭5 or Bø7. Compared with Bdim, it adds A as the seventh.

These two shapes make the seventh-tone change easy to hear: A becomes A♭. They are examples, not the only useful voicings.

03 · FULLY DIMINISHED SEVENTH

How a diminished seventh differs

A fully diminished seventh chord adds a diminished seventh, ♭♭7, to the triad. For Bdim7, the written notes are B–D–F–A♭. The ♭♭7 formula is measured against B major’s seventh, A♯. Lowering A♯ by two semitones gives A♭; the interval is a diminished seventh even though the resulting note name has only one flat.

For a longer comparison of its chord tones and guitar shapes, see the diminished seventh chord guitar section.

04 · READ AND MOVE A SHAPE

Read strings low to high before moving frets

These examples assume standard tuning, E–A–D–G–B–E, with the thick low E string first. A fret code reads from string 6 to string 1: x means mute or skip the string, and 0 means play it open. For example, x2323x leaves both E strings quiet and plays frets 2–3–2–3 on the four middle strings.

Separate the sounding pitch from its theoretical spelling. The G-string fret 1 in the Bdim7 shape on this page is written A♭3. B-double-flat (B𝄫) is enharmonic with A in equal temperament. The string and fret tell you what sounds; the chord spelling explains how that note functions.

When does moving a shape up three frets work?

The three-fret symmetry applies to a complete four-note diminished seventh chord. Moving every note in a Bdim7 shape up three frets raises each sounding pitch by a minor third; the resulting Ddim7 spelling cycles through the same pitch classes, including C♭ in place of B. The actual notes are higher, so it is not the original voicing at the same pitches.

Do not apply that shortcut to a diminished triad or a half-diminished seventh. Moving those shapes also raises their pitch classes, and those chord qualities do not contain the same four-note symmetrical set.

diminished 7 chords

The three shapes already printed on this page are candidates the chord finder generated for B. Sounding MIDI is the open-string MIDI plus the fret. From low E to high E the open MIDI numbers are 40, 45, 50, 55, 59 and 64. Semitones above the lowest root, B2 at MIDI 47, are sounding MIDI minus 47. The degree counts that pitch class from B: 0 is 1, 3 is ♭3, 6 is ♭5, 9 is ♭♭7, and 10 is ♭7.

Moving every fretted string of x2313x up by the same number keeps the pitch classes B, D, F and A♭. The finder returns x2313x for B diminished 7, and x5646x for D diminished 7. It does not return the frets six or nine higher. Those two rows are the same frets plus 6 and plus 9, not separate finder shapes. The lowest sounding note’s degree goes 1, then ♭3, then ♭5, then ♭♭7.

The D diminished 7 spelling on this page writes C♭ for the note that sounds B3. The table keeps the B diminished 7 spelling B–D–F–A♭.

Moving the same shape up three frets raises every note by 3 × 100 = 300 cents. Four of those moves are 4 × 3 = 12 frets and 4 × 300 = 1200 cents, one octave.

Counting all twelve diminished-seventh roots gives three pitch-class sets, with four roots in each set. The table uses theoretical spelling. A double flat is written with two flat signs, so the seventh of C diminished seventh is B♭♭.

An equal-tempered minor third is 2^(3/12) = 1.1892, which is 300 cents. Four of those ratios multiply to (2^(3/12))^4 = 2, and 4 × 300 = 1200 cents, one octave.

A just minor third is the ratio 6/5, which is 315.64 cents. Four of them are (6/5)^4 = 1296/625 = 2.0736, which is 1262.6 cents. 1262.6 − 1200 = 62.6, so the stack sits 62.6 cents above the octave. Stacking equal minor thirds lands on the octave only in equal temperament.

The equal-tempered diminished fifth is 2^(6/12) = √2 = 1.4142, which is 600 cents. The just ratio 45/32 = 1.40625 is 590.2 cents.

For B°7 from B3, MIDI 59, each frequency is f = 440 × 2^((m − 69) ÷ 12). B3 is 246.94 Hz, D4 is 293.66 Hz, F4 is 349.23 Hz, and A♭4 is 415.30 Hz.

05 · SLOW PRACTICE

Hear Bm7♭5 → E7 → Am in A minor

As one slow iiø–V–i example in A minor, play Bm7♭5, then E7, then Am. The chord tones are B–D–F–A, E–G♯–B–D, and A–C–E. Pause between shapes and check each note before strumming. This progression is a practice example, not a rule that every diminished chord replaces a minor chord.

For a refresher on fret codes and guitar chord diagrams, see guitar chords for beginners.

COMMON QUESTIONS

Diminished guitar chord questions