|Relative key||F minor|
|Parallel key||A-flat minor|
|Dominant key||E-flat major|
|A♭, B♭, C, D♭, E♭, F, G|
The A-flat major scale is:
The relative minor is F minor. Its parallel minor, A-flat minor, is usually replaced by G-sharp minor, since A-flat minor, which would contain seven flats, is not normally used. G-sharp major, its enharmonic, with eight sharps, including the F, has a similar problem, and so A-flat major is often used as the parallel major for G-sharp minor. (The same enharmonic situation occurs with the keys of D-flat major and C-sharp minor.) It was used quite often by Franz Schubert; twenty-four of Frédéric Chopin's piano pieces are in A-flat major, more than any other key.
Beethoven chose A-flat major as the key of the slow movement for most of his C minor works, a practice which Anton Bruckner imitated in his first two C minor symphonies and also Antonín Dvo?ák in his only C minor symphony.
Since A-flat major was not often chosen as the main key for orchestral works of the 18th century, passages or movements in the key often retained the timpani settings of the preceding movement. For example, Beethoven's Symphony No. 5 in C minor has the timpani set to C and G for the first movement. With hand-tuned timpani, there is no time to re-tune the timpani to A-flat and E-flat for the slow second movement in A-flat; accordingly, the timpani in this movement are reserved for the passages in C major. In Bruckner's Symphony No. 1 in C minor, however, the timpani are re-tuned between the first movement in C minor and the following in A-flat major.
A-flat major was the flattest major key to be used as the home key for the keyboard and piano sonatas of Domenico Scarlatti, Joseph Haydn and Ludwig van Beethoven, with each of them using the key for two sonatas: Scarlatti's K. 127 and K. 130, Haydn's Hob XVI 43 and 46, and Beethoven's Op. 26 and Op. 110, while Franz Schubert used it for one piano sonata. It was also the flattest major key to be used for the preludes and fugues in Johann Sebastian Bach's Well-Tempered Klavier, as flatter major keys were notated as their enharmonic equivalents.
Felix Mendelssohn, Johann Nepomuk Hummel, John Field, and Friedrich Kalkbrenner each wrote one piano concerto in A-flat (Mendelssohn's being for two pianos); they had the horns and trumpet tuned to E-flat. Max Bruch's Concerto for Two Pianos in A-flat minor has its last movement in A-flat major, which is the parallel major; this concerto plays with the contrast between the two keys.
Other compositions in A-flat major include: