BazzLow
ENIT
Module 5 · Lesson 4

Keys and key signatures

Understand what a key is and why each major key has its own set of sharps or flats.

Before this lesson: 5.1 The major scale formula · 3.5 Accidentals and key signatures on the staff

Lesson 3.5 showed what a key signature does on the staff. Now we can say where it comes from: it comes from the scale of the key.

What a key is

A piece is “in the key of G major” when it uses mainly the notes of the G major scale and feels resolved on G. A key is a tonic plus its scale. Other notes can still appear, written as accidentals.

Why each key has its own signature

Each major key has a fixed set of sharps or flats: the ones its scale needs. That set is its key signature. A key signature has either sharps or flats, never both.

Bass clef staffKey signatures on the bass clef staff: G major has one sharp; D major has two sharps; F major has one flat; B♭ major has two flats.♯G♯♯D♭F♭♭B♭
Key signatures on the bass clef staff: G major has one sharp; D major has two sharps; F major has one flat; B♭ major has two flats.

The 15 major keys

The 15 major key signatures, each with its scale.
Major keyKey signatureScale
C0C D E F G A B
G1 ♯G A B C D E F♯
D2 ♯D E F♯ G A B C♯
A3 ♯A B C♯ D E F♯ G♯
E4 ♯E F♯ G♯ A B C♯ D♯
B5 ♯B C♯ D♯ E F♯ G♯ A♯
F♯6 ♯F♯ G♯ A♯ B C♯ D♯ E♯
C♯7 ♯C♯ D♯ E♯ F♯ G♯ A♯ B♯
F1 ♭F G A B♭ C D E
B♭2 ♭B♭ C D E♭ F G A
E♭3 ♭E♭ F G A♭ B♭ C D
A♭4 ♭A♭ B♭ C D♭ E♭ F G
D♭5 ♭D♭ E♭ F G♭ A♭ B♭ C
G♭6 ♭G♭ A♭ B♭ C♭ D♭ E♭ F
C♭7 ♭C♭ D♭ E♭ F♭ G♭ A♭ B♭

Three pairs are enharmonic keys: the same sounds written two ways. B = C♭, F♯ = G♭ and C♯ = D♭. So there are 12 different-sounding major keys, but 15 written ones. A key that would need more than 7 accidentals, such as D♯ major with 9 sharps, is a theoretical key: it is written enharmonically instead (E♭ major).

Why different keys exist

  • singers’ ranges;
  • easier fingering on some instruments: guitar and bass favour E, A, D and G, horns favour flat keys such as B♭ and E♭;
  • the sound of open strings.
Try it

Using the shape from lesson 5.3, play the scales of G, D and A major. For each, say the sharps as you play them.

New terms

Tools

  • Bass Map: Arpeggios, circle of fifths, natural harmonics, modes and scales on the bass neck, in any key.
  • Key Chords: The chords of every major and minor key, chosen on the circle of fifths, with bass boxes and common progressions.