Diatonic Chords
Diatonic chords use only the notes of one key. Build a triad on every degree of a major scale and you always get the same sequence: major, minor, minor, major, major, minor, diminished. Learn that pattern once and you can find the chords in every major key. Follow the interactive lesson below to learn more.
Play every chord in C major
Take a scale, stack thirds on every note, and a family of chords falls out.
What you just learned
- Stack on one
Skip a note to stack thirds
Start on C, skip D and press E, then skip F and press G. C E G is the chord on the first degree.
C (D) E (F) G = IRead the full answer ↓ - Walk up
D F A comes out minor
Move up one step and repeat: D F A. Three half steps, then four, so it is minor and gets a lowercase ii.
D F A = 3 + 4 = iiRead the full answer ↓ - The row
One chord is diminished
B D F has two minor thirds, three and three half steps. It is the only diminished chord in the key.
B D F = 3 + 3 = vii° - The row
The same row in every key
Major, minor, minor, major, major, minor, diminished. That order of chords is the same in every major key.
I ii iii IV V vi vii°Read the full answer ↓ - Break it
Four and five are major
F A C is major on the fourth degree. G B D is major on the fifth, and it leans hardest toward home.
F A C = IV · G B D = VRead the full answer ↓ - Break it
Seven chords, no accidentals
All seven chords came from C major, a scale with no sharps or flats. Every note you pressed was a white key.
C D E F G A B · no ♯Read the full answer ↓
Where to go from here
Every part of the lesson, answered in full
Open any question to read the full answer.
What does diatonic mean?
Diatonic means that the notes come from the active key. C major contains C-D-E-F-G-A-B, so a diatonic chord in C major uses only those notes.
The diatonic set gives you a reference. A song may also use chromatic chords. Once you know the seven expected chords, an F minor or A7 in C major becomes a specific change that you can investigate.
How do you build the seven chords?
- 1. Write the scale - C-D-E-F-G-A-B.
- 2. Start on one degree - begin with C.
- 3. Take every other note - C-E-G forms a triad.
- 4. Repeat from each degree - start again on D, E, F, G, A and B.
This produces C, Dm, Em, F, G, Am and B diminished. The half steps in the scale determine where the major thirds, minor thirds and diminished fifth occur.
What is the chord pattern in a major key?
| Degree | I | ii | iii | IV | V | vi | vii° |
|---|---|---|---|---|---|---|---|
| Quality | major | minor | minor | major | major | minor | diminished |
| C major | C | Dm | Em | F | G | Am | Bdim |
| G major | G | Am | Bm | C | D | Em | F-sharp dim |
Uppercase numerals indicate major chords and lowercase numerals indicate minor chords. The degree symbol marks diminished quality.
The interval pattern of every major scale is identical. The chord names change when you transpose, but the order of qualities stays the same.
Why use Roman numerals?
Analyze the pattern. C-G-Am-F and D-A-Bm-G have different chord names but share I-V-vi-IV.
Transpose a song. Keep the numerals and rebuild them from the new scale instead of moving every chord by trial and error.
Find chromatic chords. Any chord that does not match the diatonic pattern becomes visible immediately.
What changes when you add sevenths?
Stack one more scale note above each triad:
| Degree | Imaj7 | iim7 | iiim7 | IVmaj7 | V7 | vim7 | viim7 flat 5 |
|---|---|---|---|---|---|---|---|
| C major | Cmaj7 | Dm7 | Em7 | Fmaj7 | G7 | Am7 | Bm7 flat 5 |
V is the only degree that naturally produces a dominant-seventh chord in a major key. G7 contains B and F. Those notes form a tritone and commonly resolve to C and E.
What jobs do the seven chords usually perform?
Tonic area. I provides the clearest stability. vi and sometimes iii can prolong or substitute for that area.
Predominant area. ii and IV move away from tonic and commonly prepare V.
Dominant area. V, V7 and vii° contain the leading tone and create the strongest return to I.
These roles describe common behavior. Bass, melody, surrounding chords and style can give one chord a different local purpose.
How do diatonic chords work in minor?
A natural minor uses A-B-C-D-E-F-G. Its triads are Am, Bdim, C, Dm, Em, F and G.
| Degree | i | ii° | flat III | iv | v | flat VI | flat VII |
|---|
Tonal minor often raises degree 7. In A minor, G becomes G sharp. Em then becomes E major, and G-sharp diminished replaces G major on degree 7.
Compare Am-Dm-Em-Am with Am-Dm-E-Am. E major contains G sharp, a leading tone one semitone below A, so the second progression has a stronger dominant resolution.
Musicians regularly combine notes from natural, harmonic and melodic minor. Minor harmony is therefore more flexible than one fixed seven-chord chart suggests.
Where do non-diatonic chords come from?
Modal interchange. F minor in C major borrows A flat from the parallel key of C minor.
Secondary dominant. A7 in C major contains C sharp and points temporarily toward Dm.
Modulation. A progression can establish another tonic strongly enough that the new key becomes the reference system.
Mark the diatonic chords first. Then explain each outside note by what it changes and where it leads.
How should you practice diatonic chords?
Write a scale, build its seven triads and say each Roman numeral aloud. Play the sequence once in C major and once in G major.
Next, transpose I-V-vi-IV through three keys. Finally, take a song you know, label its chords with numerals and circle every chord that falls outside the key.