Scales and modes
Locrian mode
The Locrian mode is the seventh mode of the major scale: 1 b2 b3 4 b5 b6 b7. Its flat fifth makes it the unstable scale of m7b5 chords.
What is the Locrian mode?
Locrian is the seventh and last of the modes of the major scale. Play the notes of C major starting from B (B C D E F G A) and you have B Locrian.
Its formula is 1 b2 b3 4 b5 b6 b7. It is the only major-scale mode with no perfect fifth: the root and the b5 form a tritone. So the tonic chord is not stable; it is a diminished chord (B D F), or with the seventh, Bm7b5. Locrian looks like Phrygian (same b2) with the fifth lowered as well.
The Locrian chord: m7b5
Locrian is the natural scale for the half-diminished chord, written m7b5 or ø. Bm7b5 contains B D F A, that is 1 b3 b5 b7.
Common Bm7b5 shape with the root on the 5th string: x2323x (B at the 2nd fret of the A string, F at the 3rd on D, A at the 2nd on G, D at the 3rd on B). With the root on the 6th string: 7x776x (B, A, D, F).
This chord shows up in two specific places: as vii in a major key (Bm7b5 in C major) and, more often, as ii in a minor key (Bm7b5 in A minor).
Where to play Locrian: the minor ii-V-i
In A minor the ii-V-i cadence is Bm7b5, E7, Am. Over Bm7b5 play B Locrian (C major notes centred on B), switch to A harmonic minor (with G#) over E7, and resolve on Am.
On the neck around the 7th fret: root B at the 7th fret of the 6th string, b2 (C) at the 8th fret of the same string, b5 (F) at the 8th fret of the 5th string. Since B Locrian and C major share their notes, you can reuse your C major fingering while aiming at B, D, F and A over the chord. Jazz players often swap C for C# (Locrian natural 2) to soften the b2.
Exercise: a Locrian riff in E
E Locrian is E F G A Bb C D. Metal loves it for the E-Bb tritone.
- On the low E string, play in eighth notes: 0, 0, 1, 0, 0, 6, 0, 1 (E E F E E Bb E F).
- Add power chords F5 (1st fret) and Bb5 (6th fret) as accents.
- Keep the open string as a pedal: a full E5 would add a B natural, which is not in the mode.
To see the whole mode, show E Locrian or B Locrian on the interactive guitar scales tool in interval view: the b2 and b5 jump out right away.
Key takeaways
- Locrian = mode 7, formula 1 b2 b3 4 b5 b6 b7.
- B Locrian has the notes of C major.
- Signature chord: m7b5 (Bm7b5 = x2323x).
- Main uses: the ii of a minor cadence (Bm7b5, E7, Am) and metal riffs over a pedal.
Frequently asked questions
Why is the Locrian mode so rarely used?
Because its tonic chord is diminished: with no perfect fifth, the ear hears no point of rest. It is mostly used over a passing m7b5 chord, rarely as the main key of a song.
What chord do you play Locrian over?
An m7b5 (half-diminished) chord, for example Bm7b5 in a ii-V-i in A minor or as the seventh degree of C major. Avoid it over a plain minor chord: the b5 would clash with the perfect fifth.
What is the difference between Locrian and Phrygian?
One note: the fifth. Phrygian has a perfect fifth (1 b2 b3 4 5 b6 b7), Locrian a diminished fifth. Phrygian can work as a home key; Locrian much less easily.
Related terms
Practise in the workshop
Take it from theory to the fretboard
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