The chords of the major scale
Harmonize the major scale and you get the same seven chord types in every key: three major, three minor, one diminished. C major's chords, the pattern, and how to play them.
The pattern, once
Build a chord on every note of a major scale and the qualities always come out in the same order: major, minor, minor, major, major, minor, diminished. Written as numerals: I ii iii IV V vi vii°. Learn that once and you know the chords of every major key.
In C major
- C — I
- Dm — ii
- Em — iii
- F — IV
- G — V
- Am — vi
- Bdim — vii°
Add the seventh to each and you get Cmaj7, Dm7, Em7, Fmaj7, G7, Am7, Bm7♭5: the sound of jazz and soul, built from the same seven notes.
In G major, and any other
G major is G A B C D E F#, so its chords are G, Am, Bm, C, D, Em, F#dim. Same pattern, one sharp. Every key is on its own page with a shape for each chord.
Which chords get used most
I, IV and V carry most songs. vi is the fourth most common, because it is the relative minor and shares two notes with I. ii and iii appear in jazz and in the second half of a chorus. vii° is rare as a chord of its own; it usually appears as the top of a V7. So a beginner who knows I, IV, V and vi in three keys can play a large share of popular music. The I–V–vi–IV progression alone accounts for a startling number of hits.