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Chord · A Dominant 7th

A7 Chord

A7 is A, C#, E and Gtense; wants to resolve down a fifth. Blues and jazz workhorse.

Hear it

A7 on every instrument

The same 4 notes, 6 sets of hands. Open a diagram for alternate shapes, audio and the mistakes to avoid.

23EADGBE
Guitar4 voicings
CDEFGAB
Piano5 voicings
1GCEA
Ukulele2 voicings
5fr1312EADG
Bass1 voicing
1142GDAE
Mandolin2 voicings
4111GDGBD
Banjo1 voicing

What A7 is made of

A7 (A seventh) is built from the notes A, C#, E, G, with the interval pattern 1, 3, 5, b7.

Stack 1, 3, 5 and b7 on a root of A and you get A, C#, E and G. That interval recipe is what makes the chord a seventh chord — move the same shape to another root and the character travels with it, which is why C7 sounds like a transposed A7.

Dominant 7th: Tense; wants to resolve down a fifth. Blues and jazz workhorse.

Spelling: the notes above are written the way a score would write them, not simplified to the nearest piano key. That is why this chord is spelled with C rather than its enharmonic equivalent.

Keys that contain A7

All 4 notes sit inside the scale of 2 keys. The roman numeral marks the degree the chord is rooted on.

Other chords on A

Same root, different colour.

The same seventh shape, moved

The identical interval recipe, built on other roots.

Questions people ask about A7

What notes are in the A7 chord?
A7 is made of A, C#, E and G — the 1, 3, 5 and b7 degrees of a seventh chord built on A.
What keys use the A7 chord?
Every note of A7 belongs to 2 keys: D Major (V), B Minor (VII). The roman numeral is the scale degree the chord is rooted on.
How do you play A7 on guitar and piano?
This page shows A7 on guitar, piano, ukulele, bass, mandolin and banjo — 15 voicings in total. Each diagram links to the full instrument page with alternate shapes, audio and common mistakes.

Learn the theory behind it

Why A7 behaves the way it does — the guides that explain the chord instead of just spelling it.

Functional Harmony: Three Roles, One EngineWhat a seventh chord is for — tension, resolution, and the seat it takes in the key.6 min readThe 12-Bar Blues — Three Chords, A Century of HitsSeventh chords are the whole sound of the blues. Twelve bars is where to hear it.7 min read