Chord Construction: Root, Third, Fifth (and Beyond)

Every chord on the guitar is built from a small set of intervals stacked on top of a root note. Once you understand the system, the difference between a major chord and a minor chord stops being mysterious. The difference between A and Am is one note: the third.

The Triad: Root, Third, Fifth

A triad is the basic three-note chord. It contains:

• Root: the note the chord is named after
• Third: a third above the root
• Fifth: a fifth above the root

For C major: C (root), E (third), G (fifth). Three notes. The chord.

Major vs Minor: The Third

The interval from the root to the third determines whether the chord is major or minor.

• Major chord: major third above the root (4 half steps)
• Minor chord: minor third above the root (3 half steps)

C major: C to E is 4 half steps (major third). C minor: C to Eb is 3 half steps (minor third). One note changes; the chord's mood changes from bright to dark.

The Fifth

The fifth is usually a perfect fifth (7 half steps above the root). In both C major and C minor, the fifth is G.

In two special cases the fifth changes:

• Diminished chord: minor third + diminished fifth (b5). C diminished is C, Eb, Gb.
• Augmented chord: major third + augmented fifth (#5). C augmented is C, E, G#.

Diminished and augmented chords are rare in pop. Most music uses major and minor triads.

Adding the Seventh

Add a seventh to a triad and you get a 7th chord. The seventh sits a third above the fifth (or a seventh above the root).

• Major 7 (maj7): root, major third, fifth, major seventh. Cmaj7 is C, E, G, B.
• Dominant 7 (just "7"): root, major third, fifth, minor seventh. C7 is C, E, G, Bb.
• Minor 7 (m7): root, minor third, fifth, minor seventh. Cm7 is C, Eb, G, Bb.

The 7th adds flavor. Major 7 sounds dreamy. Dominant 7 sounds bluesy. Minor 7 sounds soulful.

Extensions: 9, 11, 13

Stacking thirds higher gives extended chords. The 9 sits a third above the 7. The 11 sits a third above the 9. The 13 sits a third above the 11.

For C major: 9 is D, 11 is F, 13 is A. Cmaj9 = C, E, G, B, D. Used in jazz and sophisticated pop.

Slash Chords: Inverted Triads

A slash chord puts a non-root note in the bass. C/G is C major with G in the bass. The notes are still C, E, G; they're just stacked differently. See our slash chord article for more.

Sources

Chord construction is foundational music theory. References: MusicTheory.net has interactive lessons on intervals and chord building. Open Music Theory covers triad and seventh-chord construction. Berklee Online's harmony teaches chord construction as a building-block approach.

FAQ: Chord Construction Questions

What's the difference between a major chord and a minor chord?

The third. Major chords have a major third (4 half steps above the root). Minor chords have a minor third (3 half steps above the root). One note changes; the mood changes.

What is a "voicing"?

A voicing is a specific arrangement of a chord's notes across the strings. C major can be voiced as a 5-string open chord, a 6-string barre chord, or a 4-string fingerstyle voicing. Same chord, different voicings.

Do I need to know intervals to play chords?

Not for playing memorized shapes. Yes, for understanding why chords work and for figuring out unfamiliar chords. Intervals are the underlying language.

What's the simplest possible chord?

A two-note chord (a dyad). Power chords are dyads: just root and fifth. Three-note triads (root, third, fifth) are the next step up and the foundation of most harmony.

How do I figure out the notes in a chord I don't know?

Use the formula. For X minor 7: take X (root), add a minor third, add a fifth, add a minor seventh. For C minor 7: C, Eb, G, Bb.