semicord

B7 B dominant seventh chord

Notes
B D# F# A
Formula
1 3 5 b7
Semitones
0 4 7 10 above the root
Other symbols
Bdom7

B to D# is a major third (4 semitones), D# to F# is a minor third (3 semitones), F# to A is a minor third (3 semitones). A dominant seventh is a major triad plus a minor seventh (A, 10 semitones above B). It is the V chord that leads back home, and the basic chord of the blues.

B7 on the piano

C4D4E4F4G4A4B4C5D5E5F5G5A5B5C#4Eb4F#4Ab4Bb4C#5D#5F#5Ab5Bb5C4BC5D#F#A

Root position from B4: B4, D#5, F#5, A5. Middle C is C4.

B7 on the guitar

Standard tuning (E A D G B E). Strings run low E on the left to high e on the right, frets downwards; × is a muted string, ○ an open string, and each dot shows the note it sounds, with the root in blue-green. Every shape below has B as its lowest note.

×BBF#F#AAD#D#F#F#
A-shape barre, root on the A string at fret 2
x 2 4 2 4 2 (low E to high e)
Sounds B2 F#3 A3 D#4 F#4
7frBBF#F#AAD#D#F#F#BB
E-shape barre, root on the E string at fret 7
7 9 7 8 7 7 (low E to high e)
Sounds B2 F#3 A3 D#4 F#4 B4

The barre shapes are movable: an E-shape chord's root is the note under your first finger on the low E string, an A-shape chord's root is the note on the A string. Slide the same grip up or down to play dominant seventh chords on other roots.

Inversions of B7

An inversion puts a note other than the root in the bass. The name is what semicord's chord finder calls those notes played bottom to top; a slash name like C/E means a C chord with E in the bass.

PositionNotes, bass firstNamedListen
Root positionB D# F# AB7
1st inversionD# F# A BB7/D#
2nd inversionF# A B D#B7/F#
3rd inversionA B D# F#B7/A

Where B7 fits

B7 is V7 in E major, V7 in E minor. Its D# and A are a tritone apart (6 semitones). In E major the D# usually rises a half step to E and the A falls a half step, which is why B7 pulls so strongly towards E.