What is the Locrian mode?
- Half-diminished scale
Locrian is the seventh of the major scale — B Locrian uses the white keys of C major, started from B — and runs 1, ♭2, ♭3, 4, ♭5, ♭6, ♭7. It is Phrygian with one more note lowered, the fifth. A lowered fifth means the chord built on the is diminished rather than minor, so the mode never quite settles; it turns up in metal riffs and as a passing colour more than as a home.
This page is a lesson, not a poster. Read it top to bottom; every section has something to press, and the whole page follows one root and one octave — change either and everything below changes with it. If the low keys are hard to hear on your speaker, use Octave + to lift the whole lesson.
1. First, hear it
The keyboard below is locked to B Locrian. Keys with a green number are in the and play; keys with a red dot stay silent. Press Play. It opens with the same cramped half step as Phrygian, and then the fifth — the one note every other scale on this site leaves alone — comes out wrong. The run ends on the root, but the root does not feel like arriving. That is not a flaw in your ear. It is the mode.
2. Counting from home: five flats
Every scale has a home note, the — here B, and the picker above moves it. The other notes are named by how far above the root they sit: their . Count keys to the right, black and white alike; each key is one . The plain numbers 1 to 7 belong to the major scale; a (♭) means “that note, one key lower.”
| Degree | Half steps (keys) above the root | In B | What it is |
|---|---|---|---|
| 1 | 0 | B | the root — home, such as it is |
| ♭2 | 1 | C | lowered second — one key above home |
| ♭3 | 3 | D | lowered third — minor |
| 4 | 5 | E | fourth |
| ♭5 | 6 | F | lowered fifth — the changed note |
| ♭6 | 8 | G | lowered sixth |
| ♭7 | 10 | A | lowered seventh |
Five flats — every note that can be lowered, is. Only the 1 and 4 stand where the major scale put them. The ♭5 is the one no other mode of the major scale touches. Click a chip to hear each degree in B.
3. Move one key: Phrygian becomes Locrian
Take Phrygian in B and lower its 5 — F♯ — one key to F. Nothing else changes. Flip the toggle and watch one key go dark while its lower neighbour lights. Phrygian is dark but it stands up; the fifth holds it. Locrian takes the fifth away.
Locrian keeps every other note but changes 5 (F♯) to ♭5 (F). Flip the toggle and watch one key go dark while its neighbour lights up.
4. Why it cannot rest: the home chord is diminished
Build a chord on the root of any scale from its 1, 3, and 5 — a . In every other mode of the major scale that chord is major or minor, and the fifth on top makes it solid: root and fifth are the two notes a power chord is made of. Locrian’s home triad is 1 ♭3 ♭5. Its outer notes are six half steps apart — a — and the chord is diminished. Press the two chords in turn: the first settles, the second asks a question and waits.
A scale whose home chord wants to move somewhere else has no stable centre, and that is why Locrian is rare as a key. Whole pieces in it are unusual; you meet it instead as a colour — a metal riff that leans on the ♭2 and ♭5 against a low root, a bar of tension before a resolution — and, in jazz, as the set of notes that fits a half-diminished chord. That last use is why its other name is the half-diminished scale.
5. Same keys, different home: a major scale from its seventh
Now the map view. Take the seven keys of B Locrian and, without turning any on or off, call the ♭2 home instead. You are now playing the major scale on C. In B that is C major: the same white keys, settling one key higher. Flip the toggle and only the green 1 moves — and the whole scale suddenly sounds stable, because the note it now rests on has a real fifth above it.
B locrian uses exactly the same keys as C major. Nothing turns on or off — only 1 moves. Home is now B, which was the 7 of C major. Play both runs and hear how the same notes settle in a different place.
Locrian is the seventh and last of the major scale — the major scale started from its seventh degree, the leading tone. Every note in it is pulled toward the C a half step up, which is another way of saying why B never quite feels like home.
6. What to do with it
Keep the lock on and hold a low root while you play above it. Do not look for a resting note — use the instability. Lean on ♭2 → 1 and ♭5 → 4 as the two falling steps; let the ♭5 ring against the root when you want the sound of something unresolved. Then flip any comparer above back to its other side and notice how much relief one key can bring.
Quick reference
- Formula
- 1 – ♭2 – ♭3 – 4 – ♭5 – ♭6 – ♭7
- In B
- B – C – D – E – F – G – A