Keys and the circle of fifths

When a song is "in the key of G", it means the music revolves around the note G and uses (mostly) the notes of the G major scale. G feels like home; the other notes create movement away from and back to it.

Key signatures

Each major key has a specific number of sharps or flats — its key signature:

Key	Sharps / flats	Notes
C	none	C D E F G A B
G	1 ♯	G A B C D E F♯
D	2 ♯	D E F♯ G A B C♯
A	3 ♯	A B C♯ D E F♯ G♯
E	4 ♯	E F♯ G♯ A B C♯ D♯
F	1 ♭	F G A B♭ C D E
B♭	2 ♭	B♭ C D E♭ F G A

Guitar-friendly keys like E, A, D, G and C are popular because they use lots of open strings.

The circle of fifths

Arrange the 12 keys so that each one is a perfect 5th above the previous one and you get a circle. Click any key:

What the circle tells you:

• Going clockwise, each key adds one sharp. Going counter-clockwise, each adds one flat.
• The inner ring shows each key's relative minor: a minor key that uses exactly the same notes (A minor has the same notes as C major).
• Neighbors are related: keys next to each other share six of seven notes. That's why songs can easily move between them.
• The I, IV and V chords of any key are the key itself and its two neighbors. In G: G (I), C (IV) and D (V).

Relative minor

Every major key has a relative minor that starts on its 6th degree. Same notes, different home — and a darker mood:

• C major ↔ A minor
• G major ↔ E minor
• D major ↔ B minor

C major chord A minor chord

How to find the key of a song

1. Look at the chords. Which one feels like the "resting" chord? It usually starts or ends the song.
2. Look up which key contains all (or most) of the chords. If a song uses G, C, D and Em, it is in G major.
3. If it feels sad and rests on Em instead, it's in E minor (the relative minor).

In the next lessons, we'll see exactly how the chords of a key are built.