Lesson
Chord Construction: Building Harmony from Intervals
Chords are three or more notes played simultaneously, built by stacking intervals. The most basic chord is a triad: root, 3rd, and 5th. Add a 7th for seventh chords, then 9ths, 11ths, and 13ths for extensions. Understanding chord construction lets you build any chord from scratch, name chords you encounter, and create rich, sophisticated harmonies. This is the foundation of arranging and composition.
Triads
Major: root + major 3rd + perfect 5th. Minor: root + minor 3rd + perfect 5th. Diminished: root + minor 3rd + diminished 5th. Augmented: root + major 3rd + augmented 5th.
Seventh Chords
Add a 7th to triads: Maj7 (major 7th), 7 (dominant = minor 7th), m7 (minor triad + minor 7th), m7♭5 (half-diminished), °7 (fully diminished). Sevenths add color and tension.
Extensions
9th = 2nd an octave up. 11th = 4th an octave up. 13th = 6th an octave up. Extensions add richness and complexity. Jazz and neo-soul rely heavily on extended chords.
Alterations
♭9, #9, #11, ♭13—altered notes add tension and color. C7#9 is the "Hendrix chord." Alterations are common in jazz and create distinctive sounds.
Key Takeaways
- Triads = root + 3rd + 5th (major, minor, diminished, augmented)
- Seventh chords = triad + 7th (adds tension/color)
- Extensions (9, 11, 13) continue stacking thirds above the 7th
Common Mistakes
Memorizing Shapes Instead of Building from Intervals
Knowing that a Cmaj7 is "C-E-G-B" is useful, but it won't help you play Ebmaj7 without thinking. Understand the formula: major triad + major 7th. Then you can build any chord on any root instantly. Memorizing specific chord voicings is fine, but it must be in addition to—never instead of—understanding the interval formula that defines each chord type.
Always Using the Same Voicing
A Cm7 chord can be voiced in dozens of ways—closed, open, spread, inversions, with or without the root. Using root-position close voicings exclusively creates muddy, boring harmonic texture. Learn inversions (1st, 2nd, 3rd inversion) and practice voicing chords with different spacings to create smooth voice leading and interesting sonic color.
Thinking Chord Symbols Are Arbitrary
Chord symbols like Cm7b5 or G7#9 are precise interval formulas in disguise. Cm7b5 = minor triad (Cm) + minor 7th (m7) + flattened 5th (b5). Every symbol encodes a specific structure. Learn to decode chord symbols by decomposing them into their component intervals—you'll be able to build any chord you see on a chart, even ones you've never played before.
Why This Matters
Build any chord, anywhere — With interval knowledge, you can construct any chord on any root on any instrument—piano, guitar, synth, MIDI—without memorizing individual shapes for each key.
Read chord charts fluently — Lead sheets and chord charts use symbol notation. Understanding what Dm9, G13, and Abmaj7#11 mean lets you play any chart placed in front of you.
Arranging and orchestration — Understanding chord construction lets you voice chords across multiple instruments, choosing which tones each instrument plays to create optimal blend and texture.
Harmonic sophistication — Extended and altered chords define jazz, neo-soul, R&B, and modern pop. Knowing how to build them gives you the harmonic vocabulary of professional composers and producers.