Seventh Chords and Inversions

After this lesson, you will be able to spell Cmaj7, G7, Dm7, and half-diminished Bm7♭5 (also written m7♭5) accurately. You will identify root position, first inversion, second inversion, and third inversion from the bass without confusing quality, inversion, or voicing.

One more third creates a seventh chord

A seventh chord contains root–third–fifth–seventh, which can be arranged as three stacked thirds. Cmaj7 is a C-major triad plus major seventh B. G7 is a G-major triad plus minor seventh F; the plain 7 creates dominant-seventh quality, not a major seventh. Dm7 is a D-minor triad plus minor seventh C.

Bm7♭5 is half-diminished: B–D–F is a diminished triad and A forms a minor seventh above B. The m7♭5 symbol describes a minor-seventh chord with a lowered fifth; ø7 is another common analytical symbol. Do not confuse it with a fully diminished seventh chord, whose seventh is diminished.

Four positions are determined by bass

G7 is in root position with G in the bass, first inversion with B, second inversion with D, and third inversion with F. Common figures are 7, 6/5, 4/3, and 4/2, often shortened to 2. They describe intervals above the bass, not lead-sheet quality suffixes.

Slash symbols can show G7/B, G7/D, and G7/F. Read the entire expression before the slash as G7, then verify that B, D, or F belongs to G–B–D–F. Because all three do, they define genuine inversions.

Quality, inversion, and voicing answer different questions

Quality asks which pitches belong to the chord. Inversion asks which member is lowest. Voicing asks how those pitches are distributed. F3–B3–D4–G4 and F3–G3–B3–D4 are both third-inversion G7, but their spacing differs.

You do not need four close notes in a low register. Use a single bass note or open left-hand interval, then place the third and seventh in the middle register. Close stacks are useful for seeing spelling; two-hand textures should prioritize clarity and playability.

Exercise

Four chords and four G7 positions

Write the four core chords without looking, using root–third–fifth–seventh letter order. Check that Cmaj7 does not use B♭; G7 must use F natural; Dm7 uses F and C; and Bm7♭5 must contain F natural and A. Roll and then block each chord in the middle register.

For G7, play all four positions while saying root position–7, first inversion–6/5, second inversion–4/3, and third inversion–4/2. Then combine single bass notes G2–B2–D3–F3 with the remaining pitches above B3. Finish with G7/F → C/E and hear F→E and B→C. This is one clear tendency resolution in C major, not the only voicing.

Common mistakes

• Symptom: Spelling G7 as G–B–D–F♯. Correction: A plain 7 adds a minor seventh; above G, that pitch is F natural.
• Symptom: Calling Bm7♭5 "B diminished seventh" without qualification. Correction: Say half-diminished and m7♭5; its seventh is A.
• Symptom: Identifying inversion from the top note. Correction: Find the complete texture's bass G, B, D, or F first.

Frequently asked questions

How do G7 and Gmaj7 differ? G7 has F natural, a minor seventh. Gmaj7 has F♯, a major seventh. This lesson uses G7 in C major.

Is Bm7♭5 Bdim plus a seventh? Yes, with the seventh specified: add minor seventh A above B–D–F to form a half-diminished chord.

Must one hand play all four notes? No. Divide bass and upper notes between hands while preserving spelling and the inversion-defining bass.