Seventh Chords

A 7th chord is a triad with one more note stacked a 3rd above the 5th — four notes instead of three, and that fourth note's exact quality is what separates the five distinct chord types gathered in this hub. Dominant 7th (major triad + minor 7th, 10 semitones) is the sound most people mean by "bluesy" or "unresolved, wants to move" — it's the V7 chord that pulls a progression back to its tonic in both classical and blues/rock harmony, and it's also, confusingly to beginners, the "plain 7" symbol (just "C7," not "Cmaj7") precisely because dominant 7th was the first and most common 7th chord in tonal harmony's early development.

Major 7th (major triad + major 7th, 11 semitones) sounds genuinely different from a dominant 7th despite differing by only one semitone in that top note — where dominant 7 pulls toward resolution, major 7 is dreamy and stable, the signature sound of bossa nova, soft-rock, and a huge amount of R&B and neo-soul harmony. Minor 7th (minor triad + minor 7th) is the minor-family workhorse already covered from the minor-chord side in the Minor Chords hub; it shows up here again because it's genuinely also a "7th chord" by family, and jazz ii-V-I progressions (m7 - dominant 7 - maj7) are built from exactly these three qualities in sequence.

7 Suspended 4th (7sus4) swaps the chord's 3rd for a 4th (5 semitones instead of 4 or 3), which removes the major/minor distinction entirely while keeping the dominant 7th's pull toward resolution — it's a genuinely common pre-resolution color in gospel, worship, and pop ballads specifically because it delays the arrival of that 3rd for tension. Half-diminished 7th (m7b5) stacks a diminished triad (root, minor 3rd, diminished/flat 5th) with a minor 7th on top — it's the vii chord in a major key and a defining color of the minor ii-V-i progression in jazz, genuinely distinct from a fully diminished 7th chord (covered in the Diminished & Augmented Chords hub) because that flat-5th-plus-minor-7th combination, rather than a fully symmetric diminished stack, is what gives it its particular unresolved, searching quality.

Guitar carries all five of these qualities across its full 12-key, 252-chord roster; piano carries four (7, maj7, m7, m7b5 — dropping 7sus4, which is genuinely rarer in standard piano voicing practice than in guitar strumming); ukulele carries two (7 and maj7, plus m7 counted under the minor family) reflecting its narrower 10-quality working vocabulary. Every page in this hub lays out that exact root-quality pair's four-note stack and interval breakdown in full.

The physics behind dominant 7th's pull toward resolution is worth stating plainly rather than just asserting it: the interval between a dominant 7th chord's 3rd and its 7th is a tritone (6 semitones, the most dissonant interval in Western tonal harmony), and that tritone wants to resolve inward or outward to the more consonant 3rd of the following tonic chord. This is the actual mechanical reason a V7-to-I cadence sounds so conclusively "finished" — it's not a stylistic convention, it's a specific, describable voice-leading resolution of the chord's most unstable interval. Secondary Dominants covers what happens when songwriters borrow this same pulling mechanism to resolve into chords other than the actual tonic.

A jazz ii-V-I progression sequences exactly three of this hub's qualities in order — a minor 7th (ii), a dominant 7th (V), and a major 7th (I) — and that specific three-chord shape is arguably the single most common harmonic building block in jazz standard repertoire, appearing dozens of times within a single tune's chord changes. Recognizing that shape by ear, rather than by reading the chord symbols, is one of the most practically useful skills a jazz-leaning player can build from this hub's pages.

Blues harmony leans on dominant 7th chords in a genuinely different way from jazz's functional ii-V-I logic: a 12-bar blues progression typically uses dominant 7th chords on the I, IV, and V degrees of the key even though, in strict major-key diatonic harmony, only the V chord is naturally a dominant 7th (the I and IV would naturally be major 7th or plain major chords). Using dominant 7 quality on all three is a deliberate genre convention — it's part of what makes blues harmony sound bluesy rather than "incorrect" diatonic voicing, and it's a real, describable stylistic choice rather than a simplification.

Notation is worth clarifying directly since it trips up a lot of beginners reading chord charts for the first time: "C7" always means dominant 7th (never major 7th), while a true major 7th chord is written "Cmaj7," "CM7," or occasionally "CΔ7" depending on the publisher's house style. That asymmetry — the "plain" 7 symbol defaulting to dominant rather than major — traces directly back to dominant 7th being the older, more foundational chord type in the development of tonal harmony, and StrumAndKey's chord symbols throughout this hub follow that same standard convention.

The half-diminished symbol itself varies across sources in a way worth flagging: m7b5, ø7, and Cmin7(b5) all refer to the identical chord, just written with different notation conventions common to different instruction traditions (m7b5 and the flat-5 notation are more common in guitar-oriented material; the ø7 slashed-circle symbol is more common in jazz theory texts and lead sheets). StrumAndKey uses m7b5 consistently across this hub's pages for that reason.

7th chords are where a lot of players first encounter the idea that a chord symbol can genuinely change a song's emotional weight without changing its root at all — swapping a plain major triad for a maj7 on the same root instantly adds a dreamier, more suspended color; swapping it for a dominant 7 instead adds bluesy tension and forward motion. That single added note (major 7th versus minor 7th, an entire semitone apart) is doing all of that emotional work, which is a genuinely useful thing to internalize by ear rather than only as a rule to memorize.

Recorded popular music across the past century leans on 7th chords so consistently that recognizing them by ear is one of the highest-value listening skills a player can build from this hub: dominant 7ths anchor blues and early rock and roll, major 7ths anchor bossa nova and soft rock, and minor 7ths anchor funk, R&B, and a huge share of modern pop and hip-hop sampling — four genuinely distinct genre fingerprints traceable back to which single note (that one added 7th) a given chord carries.

Sampling and looping in hip-hop and electronic production frequently isolate a single 7th chord (often a maj7 or m7 voicing lifted from a jazz or soul recording) and repeat it as the harmonic backbone of an entire track, which is part of why listeners raised on sample-based production so often develop a strong, immediate ear for 7th-chord color even without any formal theory training — the chord's specific flavor becomes instantly recognizable through sheer repetition inside a genre that leans on it constantly.

Church and gospel piano and organ traditions treat 7th chords, especially dominant 7 and its extended relatives, as a near-constant harmonic vocabulary rather than an occasional color — a real, distinct stylistic lineage from classical harmony's more conservative and selective use of 7th chords, and one of the clearest genre-to-genre contrasts in how frequently this hub's five qualities actually get reached for in practice. A gospel pianist moving fluently through dominant 7ths, maj7s, and 7sus4 chords within a single verse is applying exactly the vocabulary this hub documents, just at a genre-specific density most other styles don't sustain for as long. That fluency is usually built by ear over years of playing in a church setting long before any of these players could name the chords theoretically, which is a genuine, well-documented pattern in how this hub's vocabulary actually gets learned outside formal instruction — by ear and repetition inside a real musical community, long before it gets a written name attached to it at all, and often long before the player could explain a single interval on paper — the ear leads, and the theory catches up whenever it's needed.

Guitarists and pianists voice 7th chords differently for a structural reason worth restating plainly: guitar's six strings and standard tuning often make certain notes easier to omit or double than others (a guitarist might drop the 5th from a 7th chord voicing simply because reaching it cleanly isn't practical in a given position), while a pianist's freer hand position generally makes voicing all four notes of a 7th chord straightforward in any key. That's part of why the "same" 7th chord can look and feel like a genuinely different physical task depending on which of StrumAndKey's three instrument hubs a reader is working from.

Related reading: How Chords Are Built walks through the 3rd-stacking process that generates 7th chords from triads in the first place, Chord Extensions explains what happens when a 5th or 6th note gets added on top of these four-note shapes, and Diatonic Chords explains why a major key's vii chord is specifically a half-diminished 7th and not a plain diminished triad.