Chords on the guitar
A chord is three or more notes sounding together. Almost all of them are built by stacking thirds from one note, the root. If you understand how they are formed, you can build and name any chord without memorizing it.
The triad: 1-3-5
The triad is the simplest chord: three notes that come from stacking two thirds on the root. They are degree 1 (the root), 3 (the third) and 5 (the fifth), the same degrees from the Scales lesson.
The four kinds of triad
Depending on the size of the two thirds (M3 is a major third, 4 half steps, and m3 a minor one, 3 half steps) there are four triads. The chords in the table are named as in the chord viewer.
| Type | Formula | Thirds | Notes on C | Name |
|---|---|---|---|---|
| Major | 1 3 5 | M3 + m3 | C E G | C major |
| Minor | 1 b3 5 | m3 + M3 | C Eb G | C minor |
| Diminished | 1 b3 b5 | m3 + m3 | C Eb Gb | C diminished |
| Augmented | 1 3 #5 | M3 + M3 | C E G# | C augmented |
Build a triad
Choose a root (with the # / b switch) and a triad type. You will see its notes spelled correctly, the thirds that form it and the fretboard with its notes.
- Root
- Third
- Fifth
C major: C E G. Formula 1 3 5. Thirds: M3 + m3.
The chords of the major scale
If you stack thirds on each degree of the major scale, using only the notes of the scale, you get seven triads. They are named with roman numerals: capitals for major (I, IV, V), lowercase for minor (ii, iii, vi) and a circle ° for the diminished one (vii°). The recipe is always the same: major, minor, minor, major, major, minor, diminished.
In C major they are C major, D minor, E minor, F major, G major, A minor, and B diminished.
Choose a key and switch between triads and sevenths. Each chord links to its voicings when the viewer has them.
| Degree | Chord | Notes | See voicings | Listen |
|---|---|---|---|---|
| I | C major | C E G | See voicings | |
| ii | D minor | D F A | See voicings | |
| iii | E minor | E G B | See voicings | |
| IV | F major | F A C | See voicings | |
| V | G major | G B D | See voicings | |
| vi | A minor | A C E | See voicings | |
| vii° | B diminished | B D F | See voicings |
Seventh chords
If you stack one more third onto the triad, you get a four-note chord with the seventh: 1 3 5 7. These are the four most common.
| Type | Formula | Thirds | Notes on C | Name |
|---|---|---|---|---|
| Major seventh (maj7) | 1 3 5 7 | M3 + m3 + M3 | C E G B | Cmaj7 |
| Dominant (7) | 1 3 5 b7 | M3 + m3 + m3 | C E G Bb | C7 |
| Minor seventh (m7) | 1 b3 5 b7 | m3 + M3 + m3 | C Eb G Bb | Cm7 |
| Half-diminished (m7b5) | 1 b3 b5 b7 | m3 + m3 + M3 | C Eb Gb Bb | Cm7b5 |
In the major scale, the seventh chords are Imaj7, ii7, iii7, IVmaj7, V7, vi7 and viiø7 (the ø symbol means m7b5). In C they are Cmaj7, Dm7, Em7, Fmaj7, G7, Am7, and Bm7b5.
The V7 is special: it joins the major third and the minor seventh, which form a tritone, a tension that “asks” to return to the I chord. It is the same idea as the harmonic minor, which raises the seventh to get a major or seventh chord on V.
Inversions
If the lowest note of the chord is not the root, the chord is still the same one and it is called an inversion. For example, C major with E as the lowest note is C major in first inversion. We do not go deeper here.
Major against minor
Between a major and a minor chord with the same root only one note changes: the third, which in the minor is a half step lower. The root and the fifth are the same.
- Root
- In both (the fifth)
- Only in the major (the major third)
- Only in the minor (the minor third)
C major: C E G. C minor: C Eb G. Only the third changes: E in the major and Eb in the minor, a half step lower.