Lesson 13 · All 12 keys

Dominant 7th Chord Trainer

Learn how a dominant 7th chord is built one semitone-count at a time — a major triad plus a minor 7th on top — then put it to work with two MIDI exercises: playing all 12 dominant 7th chords around the circle of fourths, and a classic blues-style four-chord turnaround built entirely from dominant 7th chords, in every key.

How a dominant 7th chord is built

A dominant 7th chord is a 4-note chord — a major triad with one more note stacked on top. Every dominant 7th chord — in any of the 12 keys — is built the exact same way, by counting semitones to the right from a root note:

  1. Start on the root — the note that names the chord.
  2. Count 4 semitones to the right to land on the major 3rd.
  3. From there, count 3 more semitones to the right (7 semitones from the root) to land on the perfect 5th.
  4. From there, count 3 more semitones to the right (10 semitones from the root) to land on the minor 7th.
Example — A dominant 7th (A7): start on A, count 4 semitones right to reach C♯, 3 more to reach E, then 3 more to reach G. A‑C♯‑E‑G is the A7 chord. The pattern 4, 3, 3 (10 semitones total from root to top) is what makes a chord "dominant 7th" — every one of the 12 dominant 7th chords is this same shape, just moved to start on a different key.
It's called "dominant" because it's the chord built on the 5th (dominant) scale degree of a major key, with that key's own 7th scale degree added on top — for example, in the key of D major, the V chord is A major, and adding D major's 7th degree (G) on top turns it into A7. That extra minor 7th creates a tense interval (a tritone) between the chord's 3rd and 7th that wants to resolve inward, which is exactly what gives V7 its strong pull back to the tonic — the single most common engine of cadences in tonal music, and the sound behind countless blues and gospel progressions too.

Try it: pick a root and build the chord step by step

Step 1 of 4
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Chord toneNoteSemitones from rootMIDI #

All 12 dominant 7th chords at a glance

ChordRoot+4 semitones → 3rd+3 semitones → 5th+3 semitones → ♭7th

This MIDI exercise plays all 12 dominant 7th chords, one after another, moving around the circle of fourths — each chord's root sits a perfect 4th (5 semitones) above the last one: C → F → B♭ → E♭ → A♭ → D♭ → G♭/F♯ → B → E → A → D → G → back to C. Every chord is played as a full 4-note dominant 7th (root, 3rd, 5th, and minor 7th together).

Chord 1 of 12
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The 12 chords, in circle-of-fourths order

#ChordRoot3rd5th♭7th

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Key of C
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Progression in C

DegreeChordNotes