Harmony
Diatonic chords
Diatonic chords are the seven chords built only from the notes of a scale by stacking thirds on each degree, such as C, Dm, Em, F, G, Am and Bdim in C major.
What are diatonic chords?
A chord is diatonic when every one of its notes belongs to the scale of the key. Take the major scale of C (C D E F G A B) and stack thirds on each note by skipping every other letter: C E G, D F A, E G B, and so on.
You get seven chords, one per scale degree. These are the chords that sound at home in a key, and most pop, rock and folk songs are written almost entirely with them.
What are the diatonic chords in C major?
The pattern is identical in every major key: major, minor, minor, major, major, minor, diminished. Add a fourth note (another third) and you get the matching seventh chords.
| Degree | Triad | Seventh chord | Notes |
|---|---|---|---|
| I | C | Cmaj7 | C E G B |
| ii | Dm | Dm7 | D F A C |
| iii | Em | Em7 | E G B D |
| IV | F | Fmaj7 | F A C E |
| V | G | G7 | G B D F |
| vi | Am | Am7 | A C E G |
| vii° | Bdim | Bm7♭5 | B D F A |
Uppercase numerals are major chords, lowercase are minor, and the small circle marks the diminished chord. This is the foundation of Roman numeral analysis. Apply the same pattern to G major and you get G, Am, Bm, C, D, Em, F#dim; in D major, D, Em, F#m, G, A, Bm, C#dim.
How to play the diatonic chords on the fretboard
In C major, all seven chords have easy shapes near the nut (low E to high E, x = muted string):
- C: x32010
- Dm: xx0231
- Em: 022000
- F: 133211 (barre at the 1st fret)
- G: 320003
- Am: x02210
- Bdim: x2343x
To see the logic on the neck, also play them as seventh chords on strings 5 to 2: Cmaj7 x3545x, Dm7 x5756x, Em7 x7978x, Fmaj7 x8 10 9 10 x. Each chord moves up one step of the scale, so your root on the A string walks up the C major scale.
How to use diatonic chords to write songs
Pick three or four diatonic chords and you already have a progression that works. Some classics in C major:
- I-V-vi-IV: C G Am F, the pop progression.
- ii-V-I: Dm7 G7 Cmaj7, the engine of jazz.
- I-vi-ii-V: C Am Dm G, the classic turnaround.
- vi-IV-I-V: Am F C G, the same colours seen from the relative minor.
To change key, keep the numerals and shift everything: with a capo at the 2nd fret, the same C shapes sound in D major. The interactive circle of fifths shows the seven chords of any key in one click, and GuitarHarmony's progression library lists them by style.
Key takeaways
- Seven chords per key, one per degree, built in thirds from the notes of the scale only.
- In major: I, ii, iii, IV, V, vi, vii° (major, minor, minor, major, major, minor, diminished).
- V is the only diatonic dominant seventh chord (G7 in C).
- Think in degrees: a progression learned in one key moves to any other key.
Frequently asked questions
How do I find the chords in a key on guitar?
Write out the major scale of the key, then apply the pattern major, minor, minor, major, major, minor, diminished. In A major (A B C# D E F# G#) that gives A, Bm, C#m, D, E, F#m and G#dim.
What are the diatonic chords in a minor key?
In A natural minor you get Am, Bdim, C, Dm, Em, F and G (i, ii°, III, iv, v, VI, VII). They are the same chords as C major, seen from the sixth degree. In practice, Em is often replaced by E or E7, borrowed from the harmonic minor scale, to get a stronger pull back to Am.
Do non-diatonic chords sound wrong?
No. A chord from outside the key adds colour or tension: E7 in C major points to Am, Fm adds a bittersweet shade, B♭ gives a rock flavour. You just need to know where it comes from so you can place it well and resolve it.
Related terms
Practise in the workshop
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