What is a Half-Diminished Chord?

A half-diminished chord is a four-note chord built from a root, a minor third, a diminished fifth, and a minor seventh. This combination of intervals creates a tense and slightly unstable sound that is commonly used in jazz and classical harmony. For example, a B half-diminished chord (often written as Bm7♭5) contains the notes B, D, F, and A.

The name “half-diminished” comes from the fact that the chord shares some characteristics with a fully diminished chord but is not as tense. A fully diminished chord includes a diminished seventh, while the half-diminished chord instead has a minor seventh. This difference gives the half-diminished chord a slightly softer and more flexible sound.

Half-diminished chords frequently appear in minor key chord progressions and are commonly used in jazz harmony. They often function as a passing chord or as part of a progression that leads to another chord, creating movement and tension before resolving. Because of their distinctive sound, half-diminished chords are an important part of advanced harmony and composition.