Key signature · 4♭
A♭ major key signature and F minor
A♭ major and its relative minor, F minor, share a key signature of four flats: B♭, E♭, A♭ and D♭.
- Flats4
- WhichB♭ E♭ A♭ D♭
- Relative minorF minor
- Home chordA♭–C–E♭
The key signature
The flats come right after the clef, on every line of music. In the treble clef: B♭ on the middle line, E♭ on the top space, A♭ on the second space and D♭ on the fourth line. In the bass clef the same flats appear, in the same order, on the bass staff’s B, E, A and D.
Each one changes that letter everywhere in the piece, in every octave and on both staves: in A♭ major, every B, E, A and D is flat, though no sign is written beside the note.
How to recognise it quickly
Look at the second-to-last flat: A♭. That’s the name of the major key, A♭ major. For the minor key, go down three half steps: F minor.
Flats always come in the same order, so four flats are always B♭, E♭, A♭ and D♭:
- B♭
- E♭
- A♭
- D♭
- G♭
- C♭
- F♭
Battle Ends And Down Goes Charles’ Father: the order of flats, the order of sharps backwards.
The A♭ major scale
A♭ – B♭ – C – D♭ – E♭ – F – G – A♭. On the piano that’s four black keys (A♭, B♭, D♭ and E♭) and three white (C, F and G). Its home chord is A♭–C–E♭.
More on this key: the A♭ major scale with fingering · the A♭ major chord
F minor, the relative minor
F minor uses the same four flats, starting from F, the sixth note of A♭ major: F – G – A♭ – B♭ – C – D♭ – E♭ – F. That’s the natural minor scale. Its home chord is F–A♭–C.
Pieces in F minor usually raise the seventh note, E♭, to E (the harmonic minor), so it leads up to F. That E is written as an accidental, not in the key signature: the natural beside the note is often the quickest clue that a piece is in F minor rather than A♭ major. Pieces also often begin or end on F or its chord.
More on this key: F minor natural minor · F minor harmonic minor · the F minor chord
Music in A♭ major and F minor
The slow movement of Beethoven’s Pathétique Sonata and Chopin’s “Heroic” Polonaise Op. 53 are in A♭ major.
Beethoven’s Appassionata Sonata is in F minor.
On the circle of fifths
One flat fewer is E♭ major, a fifth higher; one flat more is D♭ major, a fifth lower. Keys next to each other on the circle of fifths share all but one note, which is why music in A♭ major moves to them most easily.
A♭ minor, with the same home note but a minor scale, has a different key signature: seven flats, the same as C♭ major.
Quiz: name the key signature
Ten key signatures in the treble or bass clef, from all fifteen. Choose the key, or play its home note on the piano below, a MIDI keyboard or your computer keys (any octave).
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Questions
How many flats are in A♭ major?
Four flats: B♭, E♭, A♭ and D♭. Every B, E, A and D in the piece is played flat, in every octave, unless an accidental says otherwise.
What is the relative minor of A♭ major?
F minor. It shares the key signature (four flats (B♭, E♭, A♭ and D♭)) and starts on the sixth note of the A♭ major scale, three half steps below A♭.
What are the notes of the A♭ major scale?
A♭, B♭, C, D♭, E♭, F, G, A♭.
Which key has four flats?
A♭ major and its relative minor, F minor.
How do you recognise the A♭ major key signature quickly?
Look at the second-to-last flat: A♭. That’s the name of the major key, A♭ major. For the minor key, go down three half steps: F minor.
Keys, one at a time
Pianomi, a free sight-reading app for piano, brings in key signatures one at a time and notices when you play a note as if the key signature weren’t there.