Chord Construction
A chord is a group of notes played together, creating harmony. Chords are the vertical dimension of music — they provide the emotional context and structural support for melodies. Understanding how chords are built from intervals gives you the power to construct any chord in any key, on any instrument.
Chords are built by stacking thirds — taking a root note, skipping one note of the scale, taking the next, skipping another, and so on. This process creates the various chord qualities that form the harmonic vocabulary of Western music theory.
Triads: The Foundation
A triad is a three-note chord built from a root, a third, and a fifth. There are four types of triads, each with a distinct emotional quality:
- Major triad (root + M3 + P5) — C E G. Bright, stable, happy. The most common chord in Western music.
- Minor triad (root + m3 + P5) — C Eb G. Sad, dark, introspective. The essential contrast to major.
- Diminished triad (root + m3 + d5) — C Eb Gb. Tense, unstable, dissonant. Used as a passing chord.
- Augmented triad (root + M3 + A5) — C E G#. Dreamy, floating, unsettled. Creates a sense of anticipation.
The distance between the root and third determines whether the triad is major or minor. The distance between the root and fifth determines whether it's diminished (flat 5th), perfect, or augmented (sharp 5th). Our Chord Library lets you explore all four triad types in every key with audio playback.
Seventh Chords
Adding a fourth note — the 7th interval above the root — creates a seventh chord. Seventh chords are the backbone of jazz, blues, R&B, and much of classical harmony. Here are the five essential types:
| Type | Formula | C Example | Sound |
|---|---|---|---|
| Major 7 | 1-3-5-7 | C E G B | Dreamy, lush |
| Dominant 7 | 1-3-5-b7 | C E G Bb | Bluesy, tense |
| Minor 7 | 1-b3-5-b7 | C Eb G Bb | Smooth, cool |
| Half-dim 7 | 1-b3-b5-b7 | C Eb Gb Bb | Dark, fragile |
| Dim 7 | 1-b3-b5-bb7 | C Eb Gb A | Dense, suspenseful |
Extended Chords (9ths, 11ths, 13ths)
Extended chords add notes beyond the 7th, stacking additional thirds above the triad. A Cmaj9 is C E G B D — the 9th (D) is the same as the 2nd but an octave higher. A Cmaj11 adds F (the 11th), and a Cmaj13 adds A (the 13th). These extended chords are fundamental in jazz, where the 9th, 11th, and 13th add rich harmonic color.
In practice, guitarists and pianists often omit certain notes from extended chords (especially the 5th and sometimes the root) to make them playable while preserving the essential color tones. A guitarist playing a Cmaj9 voicing might play only C, E, B, and D — leaving out the G.
Suspended Chords
Suspended chords replace the 3rd with either the 2nd (sus2) or the 4th (sus4). This removes the major/minor quality of the chord, creating a floating, neutral sound:
- Csus2 = C D G (root + M2 + P5)
- Csus4 = C F G (root + P4 + P5)
Suspended chords typically resolve to the major chord — Csus4 → C, creating a satisfying pull. They're extremely common in rock, pop, and folk music. Think of the opening of "Stairway to Heaven" (Asus2) or "Pinball Wizard" (sus4 chords).
Chord Inversions
An inversion changes which note is in the bass (lowest position). A C major triad in root position has C in the bass. First inversion puts E in the bass (E G C). Second inversion puts G in the bass (G C E). Inversions create smoother bass lines and different harmonic textures, especially important on piano where close voicings are common.
On guitar, inversions are achieved through different fretboard voicings. A C major chord can be played as a standard open shape (root position), with the 3rd as the lowest note (first inversion, often played up the neck), or with the 5th as the lowest note (second inversion). Each voicing has a slightly different character while remaining harmonically the same chord.
Power Chords
Power chords contain only the root and 5th (perfect 5th interval) — no 3rd at all. Since there's no 3rd, power chords are neither major nor minor, making them incredibly versatile in rock, punk, and metal. Written as C5, D5, G5, etc. They're easy to play on guitar (just two or three strings) and form the backbone of countless rock riffs.
Putting Chords to Use
Once you understand chord construction, you can build any chord in any key. Use our Chord Library to see and hear every chord quality, explore scales to understand the diatonic chords in each key, and practice piano or guitar to develop real facility with chord shapes and voicings. Our Chord Progressions guide shows you how to combine chords into compelling harmonic sequences.