B♭ Diminished Triad

Chord Tones: B♭ Diminished Triad

Symbol: dim, ° — Formula: 1-♭3-♭5

Chord Notation

Roman numeral (e.g. I, IV, V) and Nashville Number notation are key-dependent. See Keys pages for chord function within specific keys.

Inversions

Harmonic Function

The B♭ diminished chord commonly functions as the subtonic (♭VII) in C major or subdominant in F major. Its harmonic role varies by key — in major keys it provides stable harmonic grounding.

The diminished triad features a flat third and flat fifth, creating a tense, unstable sound. It occurs naturally on the seventh degree of the major scale and resolves strongly to the tonic. The B♭ Diminished Triad specifically contains 3 notes: B♭, D♭, E (formula: 1-♭3-♭5). On piano, Bb-rooted chords start on a black key and create hand shapes that jazz pianists find ideal for voicing seventh chords and extended harmonies. Jazz standards, swing, and big band charts are heavily weighted toward Bb because it allows horn sections to play in their most comfortable range.

Common Progressions

The B♭ Diminished Triad frequently appears in these progression patterns (shown in Roman numeral notation relative to key):

• viidim-I
• iidim-V

Songs Featuring the Diminished Triad

Well-known songs where the B♭ Diminished Triad — or this chord type — plays a prominent role:

• Whole Lotta Love – Led Zeppelin (bridge)
• Killing Me Softly – Roberta Flack
• Black Magic Woman – Santana

Tuning Frequencies Across Temperaments

Frequencies shown at A=440 Hz. View full temperament data for any note.

Scales Containing the B♭ Diminished Triad

These scales include the B♭ Diminished Triad as a diatonic or characteristic chord: