Seventh chords add a fourth note — a seventh above the root — to the triad. The dominant seventh is the most harmonically powerful chord in Western tonal music. The major seventh is its lush, unresolved cousin.
THE SEVENTH CHORD
A seventh chord is a four-note chord built from a root, third, fifth, and seventh. There are five common seventh chord types in tonal music: major seventh (major triad + major seventh), dominant seventh (major triad + minor seventh), minor seventh (minor triad + minor seventh), half-diminished seventh (diminished triad + minor seventh, also written as ø7), and fully diminished seventh (diminished triad + diminished seventh, written as °7). Each has a distinctive sound and function.
THE DOMINANT SEVENTH: V7
The dominant seventh chord is the most important single chord in Western tonal music. Built on scale degree 5 (the dominant), it consists of a major triad plus a minor seventh: in C major, G-B-D-F. The addition of F (scale degree 4) to the already-tense dominant triad G-B-D creates a chord with two directional forces: B (leading tone, scale degree 7) pulls upward to C; F (scale degree 4) pulls downward to E. Together they form the tritone B-F, the most dissonant interval in the diatonic system, which resolves by contrary motion to C-E — the tonic third.
The V7 chord is distinctive by ear: its minor seventh above the major triad base gives it a characteristic richness and tension that the plain dominant triad (V) lacks. Once you know this sound, you will hear it constantly — in every Classical symphony, every jazz standard, every pop song that uses a dominant chord. In jazz, the dominant seventh is the foundation of the entire harmonic system: ii-V7-I is the most fundamental cadential formula in jazz harmony.
THE MAJOR SEVENTH: M7 OR Δ
The major seventh chord (Cmaj7 = C-E-G-B) adds a major seventh above the root of a major triad. The major seventh interval (11 half steps, one half step below the octave) is dissonant by classical standards — it creates a half-step clash between B and C. Yet this near-octave interval creates a distinctive sound: dreamy, lush, sophisticated, somewhere between resolution and continued yearning. Unlike V7, which demands resolution, Cmaj7 is stable enough to sit and be heard without needing to go anywhere. It became one of the defining sounds of jazz, bossa nova, and sophisticated popular music.
The distinction between V7 (dominant seventh) and Imaj7 (major seventh on the tonic) is a fundamental ear training skill for jazz musicians. They occur in the same key and share some notes, but their functions and sounds are different. V7 is tense and directive; Imaj7 is settled but lush.
MINOR SEVENTH CHORDS
The minor seventh chord (Cm7 = C-Eb-G-Bb) adds a minor seventh above a minor triad. In jazz harmony, the minor seventh chord is ubiquitous: the ii chord in a major key (Dm7 in C major) is almost always played as a minor seventh, and it anchors the ii-V7-I progression. Minor seventh chords have a darker, more melancholic quality than major seventh chords — the minor third at the base gives them their colour, and the minor seventh above adds a floating, unresolved quality without the directional pull of V7.
THE HALF-DIMINISHED SEVENTH AND FULLY DIMINISHED SEVENTH
Two additional seventh chord types complete the standard vocabulary. The half-diminished seventh (m7b5 or ø7) consists of a diminished triad with a minor seventh on top: Cø7 = C-Eb-Gb-Bb. It is the ii chord in minor keys and a common chromatic colour in jazz. Its sound is darker and more anxious than the regular minor seventh — the diminished fifth at the bottom gives it a characteristic tension. In a ii-V-i progression in minor (Dø7-G7-Cm), the half-diminished ii chord builds tension that resolves through V7 to the minor tonic.
The fully diminished seventh (°7) consists of stacked minor thirds: C°7 = C-Eb-Gb-A (the A is a diminished seventh from C, enharmonically equivalent to Bbb). This chord is symmetric: all intervals are minor thirds, dividing the octave into four equal parts. Like the augmented triad, the symmetry creates ambiguity — the same four notes can resolve in four different keys, making the fully diminished seventh a powerful pivot for modulation. It appears prominently in Romantic music and in jazz as a passing chord.
THE II-V-I PROGRESSION IN JAZZ
The ii-V-I progression is the most fundamental harmonic unit in jazz, appearing constantly in standards and original compositions. In C major: Dm7-G7-Cmaj7. The Dm7 (the supertonic seventh chord) functions as pre-dominant, creating smooth voice leading into G7 (with the bass moving down a fifth). The G7 then resolves to Cmaj7 with another descending fifth in the bass. The total motion creates two descending fifths in a row, which is the strongest harmonic motion in tonal music.
The ii-V-I progression can be chained across keys: a piece can move through six or seven keys by chaining ii-V-I progressions into successive key centres. This is the harmonic structure of "All the Things You Are" and many other jazz standards. Hearing the ii-V-I cycle is one of the most important skills for any musician working in jazz, and recognizing it across modulations is the next level.
INVERSION OF SEVENTH CHORDS
Seventh chords have four notes and therefore four possible inversions: root position (root in bass), first inversion (third in bass — called 6/5 in figured bass), second inversion (fifth in bass — 4/3), and third inversion (seventh in bass — 4/2 or just 2). Each inversion has a characteristic sound. Root position seventh chords sound stable and grounded. First inversion (6/5) is the most common alternative position, often used for smooth bass voice leading. Third inversion (with the seventh in the bass) creates strong downward resolution tension because the bass note must move down by step to a chord tone in the next chord.
In ear training, identifying seventh chord inversions is a Year 2 skill that follows mastery of seventh chord quality. The bass note is again the most reliable cue: where it sits in relation to the chord root tells you the inversion.
NOTATIONAL CONVENTIONS
Different musical contexts use different notational conventions for seventh chords. In classical music: Roman numerals with superscript Arabic numbers (V7, ii7, V6/5). In jazz lead sheets: chord symbols above the staff (Cmaj7, Dm7, G7, Cø7). In figured bass (Baroque): numerals below the bass (7, 6/5, 4/3, 2). Each system encodes the same information differently. For ear training purposes, the chord-symbol system is most useful because it directly captures chord quality and root. For analysis, Roman numerals indicate function within a key, which is often more relevant.
PRACTICAL EAR TRAINING SEQUENCE
Progress through seventh chords in this order: maj7, m7, V7, ø7 (half-diminished), °7 (fully diminished), maj7#5 (augmented major seventh), m(maj7) (minor with major seventh — used in jazz minor and the James Bond theme). Each type should be learned in root position first, then with inversions. Use teoria.com or EarMaster for systematic drill.
SOURCES & FURTHER READING
Open Music Theory — Seventh Chords (openmusictheory.net, CC BY-SA 4.0). Aldwell and Schachter. Harmony and Voice Leading. Schirmer/Cengage. Chapter 16: Seventh Chords. Laitz. The Complete Musician. Oxford University Press. Chapter 14. teoria.com — Seventh Chord Exercises. RealBook (Available at various music libraries) — The standard jazz repertoire collection; every chord is a seventh chord or more.