A dominant 7 guitar chord (A7)

How to play A7

Finger numbers run 1 for the index to 4 for the little finger. String names are given as players say them — the low E is the thickest string (the 6th) and the high E is the thinnest (the 1st).

1. 1st finger (index) — 2nd fret, D string
2. 3rd finger (ring) — 2nd fret, B string

• Play open: A (5th), G (3rd) and high E (1st) — strum them without fretting anything.
• Leave out: low E (6th) — start the strum below it, or damp it with the side of the thumb.

Notes and intervals in A7

A7 is built from 4 notes: A, C♯, E and G.

• A — the root (R)
• C♯ — the major 3rd (3)
• E — the perfect 5th (5)
• G — the flat 7th (b7)

Across the six strings the shape sounds A · E · G · C♯ · E from low to high, so some notes are doubled in different octaves — that is what gives an open guitar chord its width compared with the same chord on a keyboard.

What A7 is used for

A7 is A major with the ring finger lifted off the G string so the open G sounds the flat 7th. That one change turns a resting chord into a restless one: A7 is the V7 in the key of D, so it leans hard toward D, and it is the standard turnaround chord in a blues in A.

Common mistakes with A7

• Smothering the open G string. That open 3rd string is the flat 7th and the entire point of the chord — if the index finger is lying flat across the D string it will kill it.
• Fretting the B string with the middle finger. Using the ring finger keeps the middle free, which makes A and A7 a one-finger swap.
• Letting the low E ring, which buries the A root under an E.

Chords that go with A7

Same-root variations first, then the chords a fourth and a fifth away — the shapes A7 is most often played alongside.

• A major
• A minor
• D major
• D minor
• E major
• E minor