C-flat major

C♭ major is a major scale based on C♭, consisting of the pitches C♭, D♭, E♭, F♭, G♭, A♭, and B♭. Its key signature has seven flats—the enharmonically equivalent key signature B major (five sharps) is usually used instead.

C♭ major is the only major or minor key, other than theoretical keys, which has "flat" or "sharp" in its name, but whose tonic note is the enharmonic equivalent of a natural note (a white key on a keyboard instrument).

Its relative minor is A♭ minor (or enharmonically G♯ minor), and its parallel minor is C♭ minor, usually replaced by B minor, since C♭ minor's three double-flats make it generally impractical to use and its direct Enharmonic equivalent is B Major.

C♭ major is the home key of the harp, with all its pedals in the top position, and it is considered the most resonant key for the instrument. Thus, in Richard Strauss's Ein Heldenleben, the first cue for the harps is written in C♭ major even though the rest of the orchestra, having previously played in E♭ major, retains a 3-flat key signature and is now playing in B major, marked with the necessary sharps as accidentals. This use of C♭ major in harp parts when the rest of the orchestra is playing in B major is not exceptional: it is standard practice in orchestral music written in B major for harp parts to be notated in C♭ major. In Arnold Bax's symphonic poem Tintagel, the key is B major and again the harp part is always notated in C♭ major; but in this case the harp's key signature contains only 6 flats, and the necessary F♭s are notated with accidentals. In Claude Debussy's Sonata for Flute, Viola and Harp, the second movement has a middle section in B major, for which the harp part is notated in C-flat major with seven flats. In Reinhold Glière's Harp Concerto in E-flat, the middle movement is a set of variations in C-flat major.