D-flat major
Major key with five flats; relative major of B-flat minor, enharmonic to C-sharp major.
What it means
D-flat major is the major key built on the root D♭, with the scale D♭–E♭–F–G♭–A♭–B♭–C–D♭. It belongs to the flat keys and sits five steps to the flat side of C major on the circle of fifths.
Its relative minor, the minor key sharing the same key signature, is B-flat minor. Enharmonically, meaning identical in sound but written differently, D-flat major corresponds to C-sharp major with seven sharps; since D-flat major needs far fewer accidentals with only five flats, it is the version almost always notated in practice.
In the notation
D-flat major is notated with five flats: B♭, E♭, A♭, D♭, and G♭. These five lowered notes appear at the start of every line right after the clef and apply to every B, E, A, D, and G throughout the piece, unless cancelled by a natural sign or another alteration.
Musical use
As a key with many accidentals, D-flat major appears less often than keys with fewer accidentals such as C or G major, but it is particularly favored in piano repertoire, since many black keys fall comfortably under the fingers. It also appears regularly on transposing wind instruments and in certain orchestral contexts.