The Bbm7b5 chord contains B♭, D♭, F♭ and A♭. Written B♭m7♭5 or B♭ø7, it is a half-diminished seventh chord. F♭ sounds on the E key of the piano.
Build the Bbm7b5 chord by lowering the fifth of B♭m7 from F to F♭. Keep B♭, D♭ and A♭. Its formula is 1–♭3–♭5–♭7: a diminished triad plus a minor seventh. Writing F♭ preserves the fifth above B♭ even though its sounding key is E.
This spelling includes F♭. Preserve the theoretical written spelling even when an enharmonic name shares the same piano key.
Choose a position to keep the four written notes, sounding keys, bass note, playback and print reference synchronized.
Build the Bbm7b5 chord with B♭, D♭, the E pitch class for F♭, and A♭. F natural would restore the perfect fifth and produce B♭m7. This exercise checks the four pitch classes without identifying an inversion from the order of clicks.
B♭m7♭5 uses 1–♭3–♭5–♭7: B♭–D♭–F♭–A♭.
a diminished triad plus a minor seventh
Compared with B♭ diminished, add the minor seventh above the root.
A seventh chord has four chord tones and therefore four positions: root position plus three inversions. The slash symbol identifies the written bass note.
| Position | Symbol | Notes, low to high | Bass |
|---|---|---|---|
| Root position, current selection | B♭m7♭5 | B♭3–D♭4–F♭4–A♭4 | B♭3 |
| First inversion | B♭m7♭5/D♭ | D♭4–F♭4–A♭4–B♭4 | D♭4 |
| Second inversion | B♭m7♭5/F♭ | F♭4–A♭4–B♭4–D♭5 | F♭4 |
| Third inversion | B♭m7♭5/A♭ | A♭4–B♭4–D♭5–F♭5 | A♭4 |
The Bbm7b5 chord diagrams show note order and octaves without assigned fingers. D♭, F♭ and A♭ begin the three inversions. Keep F♭ in the written labels when reading the E key; changing the bass does not change the chord members.
Use the written notes, keyboard positions and playback without treating the diagram as a required hand shape.
Read left- and right-hand finger numbersOpen Music Theory
Supports: Half-Diminished Seventh chord construction, written spelling and inversion principles
Scope: Supports theory and spelling only; keyboard layouts are PianoGrid examples, and no fingering is assigned.
B♭, D♭, F♭ and A♭: root, minor third, diminished fifth and minor seventh. All four belong to the complete reference shown here.
A fifth above B♭ needs the letter F. Lowering the perfect fifth F to F♭ makes it diminished. E is the corresponding sounding key on the piano.
Both symbols identify the Bbm7b5 chord. The plain-text b means flat; the slashed circle identifies half-diminished quality.
B♭m7♭5 uses A♭, a minor seventh. B♭dim7 uses A𝄫, a diminished seventh, sounding on G. Their root, minor third and diminished fifth agree, but their sevenths differ.
Select the four pitch classes that make B♭m7♭5, then check your answer.
This one-octave exercise checks the exact four-note pitch-class set. Order and inversion do not affect the result; missing and extra notes are reported, while fingering and live performance are not assessed.
One octave, C through B. Select a key again to remove it.
Chord tones: B♭–D♭–F♭–A♭ · Formula: 1, ♭3, ♭5, ♭7
Dots mark the notes to play. C4 is middle C. Numbers identify octaves, not fingers.