The chords in a key

The major scale

C, D, E, F, G, A, B, C: the C major scale uses no sharps or flats. The distances between its notes follow a fixed pattern:

whole, whole, half, whole, whole, whole, half

Apply this pattern to any note and you get its major scale. Starting from G: G, A, B, C, D, E, F#, G. You need an F# to keep the half step at the end.

Here are the notes of C major near the nut, three per string, from the low E string to the high E string. The Cs are in orange: first play from C (A string, 3rd fret) to C (B string, 1st fret), then the whole position.

▶ Listen to the scale

Scale degrees

The notes of the scale are numbered with Roman numerals: C is I, D is II, E is III… up to B, VII. These are called degrees. Why they matter: they describe a song regardless of its key.

A chord on every degree

Build a triad on each note of the scale, using only notes from the scale (every other note: 1, 3, 5). The result is always the same, in every major key:

Degree	I	ii	iii	IV	V	vi	vii°
Type	major	minor	minor	major	major	minor	diminished
In C	C	Dm	Em	F	G	Am	B°
In G	G	Am	Bm	C	D	Em	F#°

Upper case means a major chord, lower case a minor one; the little circle means diminished. The V is often played as a seventh chord (G7 in C): it’s the chord that leads back to I.

Play the first six in order, going up. You hear a family: each chord seems to belong to the same story, and the C at the start feels like home.

Finding a song’s key

A song uses C, F, G and Am? Those are degrees I, IV, V and vi of C major: it’s in C. Another uses G, C, D and Em? G major. The last chord, and often the first, is almost always the I.

Guitarists’ keys

The five keys you’ll come across most on guitar, with their main chords:

Key	I	ii	iii	IV	V	vi
C	C	Dm	Em	F	G	Am
G	G	Am	Bm	C	D	Em
D	D	Em	F#m	G	A	Bm
A	A	Bm	C#m	D	E	F#m
E	E	F#m	G#m	A	B	C#m

Don’t try to learn it all by heart: remember the pattern (major, minor, minor, major, major, minor) and work out the chords from the scale.

You’ve got it when…

• You play the C major scale in open position and name its degrees
• You can give the chord type for each degree: major, minor, minor, major, major, minor, diminished
• You can give the chords in C, G, D, A and E major