A seventh chord is a triad with one more note stacked on top, the seventh above the root, so a three-note chord becomes a four-note one. That extra note adds colour and a touch of tension, which is why seventh chords are the backbone of jazz, soul, R&B and neo-soul. Here is how they are built, the main types worked out from C, and why they sound so much richer than a plain triad.
Real theory, explained plainly. It works the same on a piano, a guitar, or in a piano roll, in any key and any style. Nothing here needs a particular instrument.
A seventh chord is a triad with one more note stacked on top: the seventh above the root. A plain triad has three notes, the root, the third and the fifth. Add a fourth note a third higher again, and it lands on the seventh degree above the root, giving you a four-note chord.
Take C major, which is C, E and G. Keep stacking in thirds and the next note up is B. Sound all four together, C E G B, and you have Cmaj7, a C major seventh chord. The triad is still in there; the seventh sits on top and colours it.
That top note is what makes a seventh chord sound fuller and more shaded than the bare triad. Two things about it decide which kind of seventh chord you get: the quality of the triad underneath, whether it is major, minor or diminished, and whether the seventh you add is a major seventh or a slightly lower minor seventh. Different pairings give the handful of seventh chords worth knowing.
The four you meet most are the major seventh, the minor seventh, the dominant seventh and the half-diminished, also written minor seventh flat five. Each is a triad plus a seventh; which triad and which size of seventh decide the name and the mood. Here they are worked out from C.
| Seventh chord | Built from | In C | Tends to sound |
|---|---|---|---|
| Major seventh (maj7) | Major triad + major seventh | C E G B | Lush, warm and jazzy |
| Minor seventh (m7) | Minor triad + minor seventh | C Eb G Bb | Smooth and mellow |
| Dominant seventh (7) | Major triad + minor seventh | C E G Bb | Tense, wants to resolve |
| Half-diminished (m7b5) | Diminished triad + minor seventh | C Eb Gb Bb | Dark and unsettled |
A quick word on each. The major seventh is a major triad with a major seventh on top (C E G B): the seventh sits just below the root an octave up, and that closeness gives it the soft, glowing sound so common in soul and neo-soul. The minor seventh is a minor triad with a minor seventh (C Eb G Bb), rounder and more relaxed than a plain minor chord.
The dominant seventh is a major triad with a minor seventh (C E G Bb). It sounds tense and leans hard toward another chord, which is why it drives so much blues and is its own question below. The half-diminished, or minor seventh flat five, stacks a minor seventh on a diminished triad (C Eb Gb Bb): darker and more restless still, and a common step on the way home in minor keys.
There is one more worth naming. A diminished seventh (Cdim7 = C Eb Gb A) is built entirely from minor thirds, every note the same distance apart, which makes it sound evenly tense and rootless. It turns up as a passing chord and for suspense rather than as an everyday colour.
A dominant seventh is a major triad with a minor seventh on top, written simply as 7. In C that is C7 = C E G Bb: the bright C major triad, C E G, with a Bb added above it. The major triad wants to sound settled while the seventh pulls against it, and that quiet argument inside the chord is what gives it its restless, bluesy edge.
The name comes from where the chord naturally sits in a key. Build a seventh chord on the fifth note of a major scale, the degree called the dominant, and this is the shape you get. In the key of C that fifth note is G, and the chord built there is G7. Because it holds the note just below home and leans hard upward into it, a dominant seventh pulls strongly back toward the home chord, which is much of what makes a chord progression feel like it arrives.
That pull is also the sound of the blues. Swap the plain triads of a blues for dominant sevenths and you get the familiar grit under a huge amount of blues, rock and early soul. As a rough guide, if a chord sounds like it is aching to move somewhere, a dominant seventh is often what you are hearing.
Because the added seventh brings in a note that gently rubs against the rest of the chord, giving colour and a mild tension a plain triad does not have. A triad is stable and closed; a seventh chord keeps that stable triad but layers a little friction on top, and the ear reads that friction as warmth and depth rather than as a wrong note.
This is why seventh chords are the backbone of jazz, soul, R&B and neo-soul, where that shaded, unhurried quality is the whole point. Major sevenths sound lush and calm, minor sevenths sound soft and mellow, and dominant sevenths add the tension that makes music move. Reach for a seventh chord when a plain major or minor chord feels a little bare and you want more colour.
None of this is a rule you must obey. The words here, lush, tense, mellow, are rough labels, and the music around a chord shades how it lands. But as a first guide, a triad states the chord plainly and a seventh chord says the same thing with more colour, which is why so much music you love is quietly full of them.
We built ARGISH to make this quick to hear. It is a self-playing chord synth: set a key and it voices lush chords and whole progressions that stay in that key, sevenths included, so you can listen to how each one sounds and take the ones you like straight into your own track. It is a fast way to hear seventh chords move, not just how they are spelled on the page.
It runs free in your browser to try, and installs as AU, VST3, AAX or a standalone app when you want it inside your own sessions.
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