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Key

C♭ major

C♭ major is the major key with seven flats in the key signature, the key at the end of the flat series. On the piano it sounds exactly like B major with five sharps. Composers choose the spelling with fewer sharps or flats whenever they can, so C♭ major is rarely met.

Tonic
C♭
Key signature
7 flats (every note lowered)
Sounds like
B major (5 sharps)
Relative key
A♭ minor
Kind
enharmonic equivalent

The end of the flat series

The page Circle of Fifths gives the order of the flats: B♭ – E♭ – A♭ – D♭ – G♭ – C♭ – F♭. C♭ major with seven flats contains all seven. The trick for flat keys, that the tonic is the second-to-last flat, fits here too: the second-to-last of the seven flats in this series is C♭.

C♭ major scale

C♭ D♭ E♭ F♭ G♭ A♭ B♭ C♭ 1 1 ½ 1 1 1 ½

All seven notes carry a flat. C♭, F♭ and the upper C♭ are marked: C♭ and F♭ are the notes that coincide enharmonically with B and E. On the keyboard you play the same keys as in B major.

Enharmonic: B major

At the bottom of the circle of fifths, according to the page, three pairs of keys describe the same notes and are written differently. One of them is B major with five sharps, equal to C♭ major with seven flats. The page explains why one or the other is written: composers choose the spelling with fewer sharps or flats whenever possible, because it is easier for musicians to read. For B major that means five instead of seven.

KeyKey signatureEnharmonically equal
B major5 sharpsC♭ major
C♭ major7 flatsB major
F♯ major6 sharpsG♭ major
C♯ major7 sharpsD♭ major

This “same notes, other names” is trained by the module Enharmonic Matching.

Why have C♭ major at all?

As a key on the page, C♭ major is above all an entry in the circle's conceptual framework: it shows that the series of keys with flats reaches its limit at seven. Beyond that, as with F♭ major, keys exist only on paper and would mostly be rewritten to avoid double accidentals.

Try it yourself: Play the scale once as B major and once as C♭ major. The keys are the same; only the notation changes. Read both versions slowly and think about which you would rather play.

Continue on Maikstrings

Circle of fifths

Enharmonic equivalents at the bottom of the circle.

Enharmonic Matching

The same notes, different names.

Key Signatures

Quiz on key signatures and keys.

Related terms

A♭ majorCircle of fifthsKeyAccidentalRelative key

Editor: Maik Krohm · reviewed on 3 October 2026

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