What is a seventh chord?

A seventh chord is a four-note chord built by adding a note a seventh interval above the root to a triad. The five core types taught here are major 7th, minor 7th, dominant 7th, diminished 7th, and half-diminished (m7b5).

What is the difference between a major 7th and a dominant 7th?

A major 7th chord has a major triad plus a major seventh (11 semitones from the root), giving a smooth, jazzy sound. A dominant 7th has a major triad plus a minor seventh (10 semitones), creating tension that wants to resolve.

Seventh Chords | Free Music Theory Lesson

A seventh chord takes a triad and adds one more note - a seventh interval above the root. Four notes instead of three.

Adding the seventh introduces another interval above the root and can change the chord's function or colour. The effect depends on the chord quality, voicing, and how it connects to the following harmony.

How seventh chords are built

Start with any triad, then stack another third on top. The type of triad and the type of seventh create different combinations.

Root

C

3rd

E

5th

G

7th

B the added chord tone

The five main types

Each type has a distinct character. Tap to hear them.

Major 7th (maj7)

Major triad + major 7th. Smooth, dreamy, warm. Common in jazz and neo-soul.

Minor 7th (min7)

Minor triad + minor 7th. Mellow, slightly melancholic. Everywhere in R&B and lo-fi.

Dominant 7th (7)

Major triad + minor 7th. Tense, wants to resolve. The engine of blues and funk.

Diminished 7th (dim7)

Diminished triad plus diminished 7th. Its stacked minor-third structure is symmetrical, and its chord tones can create strong semitone tendencies toward a neighbouring chord.

Half-diminished 7th (m7b5)

Diminished triad + minor 7th. Tense but less extreme than full dim7. The naturally occurring vii chord in major keys. Common in jazz and bossa nova.

Major 7 vs Dominant 7

These two are easy to mix up. Both start with a major triad - the only difference is whether the seventh is major or minor.

Major 7th (B) versus minor 7th (Bb).

Try it

Start with the C major triad, C-E-G. Add B to make Cmaj7, then replace B with Bb to make C7. Tap both and listen for the difference between the smoother major seventh and the stronger dominant pull.

In both chords the triad stays the same. Only the seventh changes.

Why seventh chords matter

Triads sound complete but simple. Seventh chords add colour and movement. They're what separate a basic progression from one that sounds rich and professional.

Key takeaway

Seventh chords = triad + a 7th. Five main types: maj7 (dreamy), min7 (mellow), dominant 7 (tense), dim7 (dramatic), m7b5 (jazz tension). The added seventh changes the chord's interval content.

Next: going even further with 9ths, 11ths, and 13ths - extended chords.

Generate seventh chord progressions

Starts supports maj7, min7, dom7, and more chord types in MIDI export.

Seventh Chords