What Is a Dominant 7th Chord?

Updated · The Acoustic Guitarist

A dominant 7th chord is a major triad plus a flat 7th, 1 3 5 ♭7. D7 is D F♯ A C. It is called dominant because it forms on the 5th degree of a major key, the dominant, and it pulls strongly back to that key's home chord, so D7 leads to G.

On this page 8
  1. D7 on guitar
  2. How a dominant 7th is built
  3. Why it pulls back home
  4. The V7 chord in each common key
  5. Open dominant 7th shapes
  6. Movable shapes: any dominant 7th
  7. Dominant 7ths in the blues
  8. Dominant 7th or another 7th?

D7 on guitar

The open D7 uses the top four strings only. The second shape is an A7 shape barred at fret 5, with the root on the A string. The third is an E7 shape barred at fret 10, with the root on the low E string. All three sound the same four notes, D, F♯, A and C, in different orders and octaves.

How a dominant 7th is built

ToneInterval from the rootSemitonesIn D7
1Root0D
3Major 3rd4F♯
5Perfect 5th7A
♭7Minor 7th10C

It is a major chord with one extra note, two frets below the octave of the root. That ♭7 is what separates it from a major 7th chord, where the 7th is only one fret below the octave.

Why it pulls back home

Between the 3rd and the ♭7 of a dominant 7th is a tritone: six semitones, an unstable interval that wants to move. In D7 that is F♯ and C. Resolving to G, F♯ rises a half step to G and C falls a half step to B. G and B are the root and 3rd of G major, so the ear hears the move as arriving home.

That is why V7 to I is one of the strongest-sounding changes in tonal music, and why chord sheets often use D7 instead of D just before a return to G. Play the two cards in order:

The V7 chord in each common key

Find the 5th note of the key’s scale and build a dominant 7th on it.

KeyV7 chordNotes
C majorG7G B D F
G majorD7D F♯ A C
D majorA7A C♯ E G
A majorE7E G♯ B D
E majorB7B D♯ F♯ A
F majorC7C E G B♭

Minor keys use the same chord. Their V chord is made major by raising the 7th note of the scale, so A minor uses E7 and E minor uses B7. See the key of G major for D7 resolving to G in a full set of chords.

Open dominant 7th shapes

Six dominant 7ths have open shapes. They are part of the standard cowboy chord set and the most used 7th chords on acoustic guitar.

  • E7: the E chord with the ring finger lifted, so the open D string adds the ♭7.
  • A7: the A chord with the G string left open (G is the ♭7).
  • G7: G with F on the high e string, fret 1, instead of G at fret 3.
  • C7: C with B♭ added on the G string, fret 3.
  • B7: no open B major exists, but B7 is an easy open shape and the V7 of E.

Movable shapes: any dominant 7th

Two barre shapes give every dominant 7th on the neck. Find the root on the low E string or the A string and put the barre on that fret.

ShapeRoot onFret for G7Fret for C7Fret for D7
E7 shapeLow E string3810
A7 shapeA string1035

Dominant 7ths in the blues

A 12-bar blues uses a dominant 7th on all three main chords, I7, IV7 and V7. In A, that is A7, D7 and E7: three open shapes.

Bars 1–4Bars 5–8Bars 9–12
A7 A7 A7 A7D7 D7 A7 A7E7 D7 A7 E7

This is the basic form. Common variations play D7 in bar 2 (a “quick change”) or A7 in bar 12 when the song ends. Here the dominant 7ths are not resolving to a home chord; they are the home sound. The bluesy edge comes from ♭7s that sit outside the major key: G in A7 and C in D7.

Dominant 7th or another 7th?

  • G7 = dominant 7th, G B D F.
  • Gmaj7 = major 7th, G B D F♯. Softer, does not pull anywhere.
  • Gm7 = minor 7th, G B♭ D F. The minor version.
  • G9, G13 = dominant 7ths with extra notes on top. They keep the F and do the same job.

A plain number after the letter always means a dominant chord. The full family is compared in what are 7th chords.

FAQ

Why is it called a dominant 7th?

The 5th degree of a scale is called the dominant. Stack 3rds on it in a major key and you get a major triad with a flat 7th, so this chord type takes its name from that degree. In G major the dominant is D, and the chord is D7.

What is the difference between D7 and Dmaj7?

D7 has C, a flat 7th, and sounds restless. Dmaj7 has C♯, a major 7th, and sounds soft and settled. They are different chords with different jobs.

Do I play the 7 in E7 on a specific string?

In open E7 (0 2 0 1 0 0) the 7th is the open D string. You can also add D on the B string at fret 3 for a brighter E7; both are correct.

Can a minor key have a dominant 7th?

Yes. Minor keys usually raise the 7th note of the scale so that the V chord is major. In A minor the V7 is E7 (E G♯ B D), which leads back to Am.

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