Tools / Chords / B 7th flat 5

B 7th flat 5 chord on bass (B7♭5)

Also written B7♭5, B or B Dominant 7th Flat 5

B 7th flat 5 contains B, D♯, F and A. The 7th-fret shape sits high on the neck, where the frets are closer together and the stretch feels easier.

7th fret7-8-7-8

Positions on the neck1 of 3

How it’s built

B1Root

D♯3Major 3rd

F♭5Diminished 5th

A♭7Minor 7th

Formula 1, 3, ♭5, ♭7

Positions on the neck1 of 3

Inversions

The same three notes, with a different one in the bass.

Root positionB–D♯–F–AB7♭5Bass B

First inversionD♯–F–A–BB7♭5/D♯Bass D♯

Second inversionF–A–B–D♯B7♭5/FBass F

Third inversionA–B–D♯–FB7♭5/ABass A

Why it sounds like that

B 7th flat 5 is built from the formula 1, 3, ♭5, ♭7. The diminished 5th between B and F gives the chord its tense colour. Compare it with B 7th, where the 5th is perfect.

What goes wrong with B 7th flat 5?

Letting the pinky collapse on the 1st string, which mutes the A at fret 8.
Pressing the ring finger too flat on the 3rd string, so it deadens the 2nd string next to it.
Striking the open 5th string, which is not part of the chord and adds an unwanted B.

When to use it

B 7th flat 5 works as a dominant chord in jazz and blues, often resolving to E major or E minor. Use it over B 7th when the melody carries a ♭5. Its tense sound suits turnarounds and passing chords.

Changing to and from B 7th flat 5

Move to A 7th flat 5 by sliding the shape down two frets to the 5th fret.
Move to C 7th flat 5 by sliding the shape up one fret to the 8th fret.

Which voicing to use

The 7th-fret shape keeps B in the bass for a root-position sound. The B7♭5/F inversion at fret 1 or 13 puts the ♭5 in the bass, creating a darker, less stable feel.

How do you play a B 7th flat 5 chord on bass?

7th fret

Intermediate● On the diagram

B 7th flat 5 is played at the 7th fret as 7 8 7 8: index finger on the E string at fret 7, ring finger on the A string at fret 8, middle finger on the D string at fret 7 and pinky finger on the G string at fret 8.

Tip — The 7th-fret shape requires the pinky to reach fret 8 on the 1st string while the index holds fret 7 on the 4th string, stretching the left hand.

String-by-string breakdown

String	Fret	Finger	Note
4 (E)	7	1	B (1)
3 (A)	8	3	F (♭5)
2 (D)	7	2	A (♭7)
1 (G)	8	4	D♯ (3)

B7♭5/F inversion · fret 1

Intermediate

B 7th flat 5 is played at the 1st fret as 1 2 1 2: index finger on the E string at fret 1, ring finger on the A string at fret 2, middle finger on the D string at fret 1 and pinky finger on the G string at fret 2.

String-by-string breakdown

String	Fret	Finger	Note
4 (E)	1	1	F (♭5)
3 (A)	2	3	B (1)
2 (D)	1	2	D♯ (3)
1 (G)	2	4	A (♭7)

B7♭5/F inversion · fret 13

Intermediate

B 7th flat 5 is played at the 13th fret as 13 14 13 14: index finger on the E string at fret 13, ring finger on the A string at fret 14, middle finger on the D string at fret 13 and pinky finger on the G string at fret 14.

String-by-string breakdown

String	Fret	Finger	Note
4 (E)	13	1	F (♭5)
3 (A)	14	3	B (1)
2 (D)	13	2	D♯ (3)
1 (G)	14	4	A (♭7)

Common questions

How is B 7th flat 5 written?

B 7th flat 5 is written B7♭5 or B. The symbol B is also used, and the chord is sometimes called Dominant 7th Flat 5.

What is the difference between B7♭5 and B7?

B7♭5 has a diminished 5th (F) instead of the perfect 5th (F♯) in B7. That one note changes the chord from bluesy to tense and unresolved.

Can B7♭5 be used in place of B7?

B7♭5 can replace B7 when the melody or solo uses the ♭5. In a standard blues, the ♭5 may clash with the expected perfect 5th, so use it selectively.

String

Fret

Finger

Note

4 (E)

B (1)

3 (A)

F (♭5)

2 (D)

A (♭7)

1 (G)

D♯ (3)

String

Fret

Finger

Note

4 (E)

F (♭5)

3 (A)

B (1)

2 (D)

D♯ (3)

1 (G)

A (♭7)

String

Fret

Finger

Note

4 (E)

F (♭5)

3 (A)

B (1)

2 (D)

D♯ (3)

1 (G)

A (♭7)