Keys that have Signatures

Major Minor Major Minor Major Minor
A a a A a
B b B b
C c C c C
D d d D
E e E e
F f F f
G g g G

Facts to Remember

  • From the circle of fourths / fifths we have:
    • Each sharp signature is a subsequence of F C G D A E B and starts with F.
      • These are fifths.
    • Each flat signature is a subsequence of B E A D G C F and starts with B.
      • These are fourths.
    • Except for accidentals, each sequence is the other, reversed.
  • All natural keys have a signature, major and minor.
    • C and a are the only natural keys with no sharps or flats in their signature.
    • All other natural major keys except F have a sharp signature.
      • Conversely, F is the only natural major key with a flat signature.
    • Most natural minor keys have a flat signature.
      • b and e are the only natural minor keys with sharp signatures.
      • a, already mentioned, has neither sharps nor flats.
      • The remainder, c, d, f, g have flat signatures.
  • F and C are the only sharp major keys.
  • b and e do not exist. All other sharp minor keys do.
    • Neither do B and E.
    • Therefore, no sharp white piano key has a key signature, major or minor.
    • a d and g have no parallel major keys.
  • Except that of F, all flat signatures have a flat root, major or minor.
  • F and f do not exist. All other flat major keys do.
    • F is the only flat white piano key having no major signature.
      • The other, C, has.
    • Neither flat white piano keys, f and c have a minor signature.
  • C, D and G have no parallel minor keys.
    • The remaining flat minor keys, a, b, and e, exist.
  • Given a natural major key not F, its seventh is the last sharp in its signature.
    • Example. The seventh of B is A so its signature is F C G D A.
    • Example. The seventh of G is F so its signature is F.
    • Example. The signature F C G is A major since a half-step up from the last sharp, G, is A. (The major seventh, or leading tone, is a half-step below the root.)
    • The signature of F is B
  • Given a flat major key (that exists), it is the second to last flat in its signature.
    • Example. The signature of B is B E.
    • Example. The signature of E is B E A.
    • Example. The signature of A is B E A D.
    • Example. The signature of F is, oops, doesn't exist. (Use E instead.)
  • Each minor key has the same signature as its relative major.
    • The relative major of a minor key is its (minor) third.
    • The relative minor of a major key is its (major) sixth.
  • Given a minor key (that exists), find its signature.
    • Example. The (minor) third of a is c so its signature is G D A E B F C, same as C.
    • Example. The signature of e is, oops, doesn't exist. (Use f instead.)
    • Example. The third of g is b so its signature is B E, same as B.
  • Given a major key (that exists), find its relative minor.
    • Example. The sixth of F is d, its relative minor. Its key signature is the same as F: B.
    • Example. The sixth of G is c, its relative minor. Its key signature is the same as G: B E A D G C.