This list of symphonies by key is a list of symphonies sorted by key. For the least often used keys in orchestral music, the symphony listed might be famous only for being in that key.
In the Classical period, C major was the key most often chosen for symphonies with trumpets and drums. Even in the Romantic period, with its greater use of minor keys and the ability to use trumpets and drums in any key, C major remained a very popular choice of key for a symphony. The following list only includes the most famous examples.
The key of C minor was, like most other minor keys, associated with the literary Sturm und Drang movement during the Classical period. But ever since Ludwig van Beethoven's famous Symphony No. 5, Op. 67, of 1808, C minor imparts a symphony in the key a character of heroic struggle. Early classical symphonies in the key typically ended in C minor but with a picardy third for the very final chord. Following Beethoven's precedent, most C minor symphonies of the Romantic period end in C major. Another option is to end in E-flat major (the relative key), as Mahler does in his Second Symphony.
Even by Mahler's time symphonies in C-sharp minor were rare. Some of the works listed below might have no claim to fame besides being in this key.
Symphonies in D-flat major are much rarer than those in C-sharp minor and one has to look beyond the standard core repertoire to find them.
Baroque and Classical symphonies in D major typically used horns in D (reading a seventh down) and when they used trumpets, trumpets in D reading a step up. The following list includes only the most famous of the Classical and Romantic periods.
Baroque and Classical symphonies in D minor usually used 2 horns in F (whereas for most other minor keys 2 or 4 horns were used, half in the tonic and half in the relative major). Michael Haydn's Symphony No. 29 in D minor is notable for using two trumpets in D (the horns are in F but change to D for the coda of the finale). In the Romantic era, D minor symphonies, like symphonies in almost any other key, used horns in F and trumpets in B-flat.