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Key

A♯ minor

A♯ minor is the minor key on the tonic A♯ with seven sharps in the key signature: F♯, C♯, G♯, D♯, A♯, E♯ and B♯. Its relative key is C♯ major. On the piano it sounds exactly like B♭ minor, which needs only five flats in its key signature and is therefore written far more often.

Tonic
A♯
Key signature
7 ♯ (F♯, C♯, G♯, D♯, A♯, E♯, B♯)
Tonic chord
A♯–C♯–E♯
Dominant
E♯ major, E♯–G double sharp–B♯
Leading tone
G double sharp
Relative key
C♯ major
Sounds like
B♭ minor

Seven sharps and a double sharp

With seven sharps A♯ minor is the minor key at the very edge of the usual key signatures. Every degree carries a raising, the B and the E too: B♯ sounds like C, E♯ like F. For the close the seventh degree, G♯, is raised once more by a semitone. For that you need a double sharp: G double sharp. The note sounds like A and is the leading tone to the tonic A♯.

Natural minor

A♯ B♯ C♯ D♯ E♯ F♯ G♯ A♯ 1 ½ 1 1 ½ 1 1

All seven degrees carry a sharp, which is why the second degree is called B♯ rather than C and the fifth E♯ rather than F. They are the notes of C♯ major, played from A♯.

Harmonic minor

A♯ B♯ C♯ D♯ E♯ F♯ G♯♯ A♯ 1 ½ 1 1 ½ 1½ ½

The seventh degree G♯ is raised to G double sharp. The G double sharp is the leading tone, a semitone below A♯, and sounds like A. Between F♯ and G double sharp lies the augmented second.

In the glossary: Harmonic minor · Relative key

Chords and cadence

A♯miD♯mivE♯VA♯mi
DegreeNatural minorWith G double sharp (harmonic)
iA♯m A♯–C♯–E♯A♯m A♯–C♯–E♯
ii°B♯° B♯–D♯–F♯B♯° B♯–D♯–F♯
IIIC♯ C♯–E♯–G♯C♯+ C♯–E♯–G double sharp, augmented
ivD♯m D♯–F♯–A♯D♯m D♯–F♯–A♯
v / VE♯m E♯–G♯–B♯E♯ E♯–G double sharp–B♯
VIF♯ F♯–A♯–C♯F♯ F♯–A♯–C♯
VII / vii°G♯ G♯–B♯–D♯G double sharp° G double sharp–B♯–D♯, diminished

Why B♭ minor is written

A♯ minor and B♭ minor are the same key on the piano. B♭ minor has only five flats as its key signature (B♭, E♭, A♭, D♭, G♭), A♯ minor seven sharps and in addition needs the double sharp. That is why B♭ minor is usually written, and A♯ minor appears rather as a theoretical key, for instance as a way station of a modulation. More under Enharmonic equivalence.

Practice: Play the cadence in the listening example at the piano and then the same sequence in B♭ minor (B♭ minor, E♭ minor, F major, B♭ minor). You will find that the piano keys are the same. In Enharmonic Matching you train recognising such twins.

Continue on Maikstrings

Circle of fifths

Where enharmonics begin at seven sharps.

Enharmonic Matching

Notes that sound the same with different names.

The leading tone

Why minor has to borrow a leading tone.

Related terms

C♯ majorB♭ minorD♯ minorG♯ minorRelative keyMinorHarmonic minorEnharmonic equivalenceCircle of fifths

Editor: Maik Krohm · reviewed on 3 October 2026

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