Closely related keys · Keys and key signatures · Music theory
The closely related keys of a key are those that differ from it by one accidental at most. They are its relative, the key of its dominant, the key of its…
Closely related keys
The closely related keys of a key are those that differ from it by one accidental at most. They are its relative, the key of its dominant, the key of its subdominant and the relatives of those two. They are the keys to which music modulates most naturally.
Those of C major are A minor (its relative), G major (its dominant) and E minor (the relative of G), F major (its subdominant) and D minor (the relative of F). Those of A minor are C major, E minor, G major, D minor and F major.
On the circle of fifths you see them at a glance: they are the keys right next to ours, on each side and in the inner circle. They work as a map for analyzing a piece, because nearly all the modulations in a classical work go to them.
Finding them without memorizing
The closely related keys are all the keys whose signature is one accidental away, plus the relative itself. The method is short.