B7 chord on guitar
B7 (B dominant 7th) is a dominant 7th chord built on B. It has 4 notes, B, D♯, F♯ and A, and its formula is 1 3 5 ♭7.
Notes and intervals of B7
From the root upwards, B7 contains root (B), major 3rd (D♯), perfect 5th (F♯) and minor 7th (A). Those intervals give the chord its colour: the formula 1 3 5 ♭7 works the same way in every key, so once you know it for B you can build the chord on any note.
| Degree | Interval | Note |
|---|---|---|
| 1 | root | B |
| 3 | major 3rd | D♯ |
| 5 | perfect 5th | F♯ |
| ♭7 | minor 7th | A |
How to play B7 on guitar
The first shape above reads x 2 1 2 0 2 from the low E string to the high E string (x means you do not play that string, 0 is an open string). The lowest note you play is B. The other diagrams show the same chord higher up the neck: pick the one closest to the chords before and after it in your song.
Let the open strings ring: strum slowly once and check that every note sounds clean before you speed up.
Which keys use B7?
You find B7 as a diatonic chord in E major (V7). The most common case is E major, where it plays the role of V7.
Scales to play over B7
To improvise over B7, start with B Mixolydian mode. All of these scales contain every note of the chord: B Mixolydian mode. Aim for the chord notes on strong beats and use the other notes to move between them.
About dominant 7th chords
A major triad plus a minor seventh: 1 3 5 ♭7. The third and the seventh form a tritone, the unstable interval that wants to resolve, which gives the dominant seventh its tension and its bluesy edge. On its own it sounds unfinished; followed by the chord a fifth below, it sounds like an arrival. For example C7: C E G B♭.
Its main job is V7 to I, the strongest cadence in tonal music (for example G7 to C). It also works as a secondary dominant: V7 of V, V7 of vi and so on. In the blues every chord can be a 7, I7 IV7 V7 for the whole 12-bar form, and jazz uses it in ii7 V7 Imaj7.
Open shapes such as E7, A7, D7, G7, C7 and B7 come first. The movable ones come from the barre chords: the E-shape 7 (♭7 on the 4th string) and the A-shape 7 (♭7 on the 3rd string). For blues and jazz, three-note shells (root, 3, ♭7) with the root on the 6th or 5th string are very handy.
The big one: 7 is not maj7. A plain 7 always means a minor seventh (B♭ in C7), maj7 means a major seventh (B in Cmaj7), and the two sound opposite, tense versus calm. Also, inside a major key only the V chord is naturally a dominant 7; elsewhere it is a borrowed colour or a secondary dominant.
Frequently asked questions
What notes are in the B7 chord?
B7 (B dominant 7th) contains B, D♯, F♯ and A. In intervals: root (B), major 3rd (D♯), perfect 5th (F♯) and minor 7th (A).
How do you play B7 on guitar?
The easiest shape is x 2 1 2 0 2, from the low E string to the high E string. This page shows 3 positions with finger numbers.
What scale goes with B7?
B Mixolydian mode fits B7 best. Other scales that contain all its notes: B Mixolydian mode.
What key is B7 in?
B7 belongs to E major (V7). In E major it is the V7 chord.
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