F♯ Half-diminished Chord: Notes, Voicings, and How to Play It

Most players meet their first half-diminished chord in a minor ii, V, i, and for a guitarist that cadence is almost always in E minor. The reason is blunt: in that key the tonic and the dominant are open chords a beginner already owns, so the only obstacle in the whole cadence is the ii. It turns out to be barely an obstacle. Take the open A minor grip, stop the sixth string at the second fret, and every note sounding belongs to F♯m7♭5, with two strings still ringing open.

Try It: F♯m7♭5 in the Chord Finder

Set the root to F♯, sound the diminished triad, then add E and hear the edge come off it.

The Notes of F♯m7♭5

Written out: F♯, A, C, E. One black key and three white ones, and the C is the note doing everything. Look at where it puts the chord in the key signatures: F♯ minor, A major and E major all insist on C♯, so a C natural throws this chord straight out of the sharp keys its root belongs to and into G major, which carries a single sharp. Same root, one note a semitone lower, and the chord has changed neighbourhood on the circle of fifths.

Also written F♯ø7, and read aloud as F♯ half diminished or F♯ minor seven flat five.

How F♯m7♭5 Is Built

Start from the F♯ diminished triad, F♯, A and C, and put E on top, ten semitones above the root. That E is a minor 7th, and it is the only thing standing between this chord and the fully diminished seventh, which puts E♭ there instead. One semitone separates the two symbols, so it is worth being precise about what it buys.

F♯dim7 holds two tritones, F♯ against C and A against E♭, stacked in a shape so regular that one grip serves four chords. F♯m7♭5 holds exactly one, F♯ against C. Standing on top of the root is A, C and E, an ordinary A minor triad, so the chord contains a consonance the diminished seventh cannot: all of its unease lives in the relationship between the bass note and one note above it. Four notes, one point of friction, and nothing symmetrical about the arrangement at all.

Against F♯m7 the difference is the fifth, C♯ against C. The minor seventh is a chord that can be a tonic. Flatten its fifth and it stops being able to sit still.

The Other Name for These Notes

Rotate the notes so A is lowest and they read A, C, E, F♯, which is Am6, and that page sets out the identity from the other side. What matters here is that the two names are not interchangeable when you are analysing anything. A chart in E minor that prints Am6 where this chord belongs has hidden its own cadence, because the ii of E minor is built on F♯ and nothing else explains why B7 follows. Write the name that matches the function, not the one that matches the fingers.

F♯m7♭5 on the Piano

Split it across the hands and the chord becomes trivial. Left hand takes F♯, the only black key here and the one immediately left of G. Right hand takes A, C and E, which is the second triad most people ever learn. Neither hand is holding anything difficult, and neither hand contains the tritone: F♯ and C are in different hands, so the dissonance exists only when both play.

In one hand, right hand 1, 2, 3, 5 on F♯, A, C and E works, with the thumb on the raised key and everything else flat on the white row. The span is a minor 7th, so nothing has to stretch.

The resolution is what to practise, and it is almost free at the keyboard. Move to B7, B, D♯, F♯ and A: F♯ and A stay exactly where they are, C steps down to B on the white row, and E steps down to D♯, which is the black key it is already touching. Two fingers hold, two fingers drop a semitone each, and one of them barely travels at all. Do it slowly and the reason this cadence sounds inevitable stops being a theoretical claim.

F♯m7♭5 on the Guitar

The cheapest form uses the second fret and the first. Bar the middle finger across the sixth, fifth, fourth and third strings at the second fret, put the index on the second string at the first fret, and let the top string ring: 2 x 2 2 1 0 sounds F♯, E, A, C, E. The fifth string sits under the bar but is not struck. Let the fifth string ring open instead, 2 0 2 2 1 0, and you have the full open A minor shape with a thumb hooked over for the bass note.

That relationship is exact and worth keeping. The open A minor chord plus an F♯ bass is this chord; the open A major chord plus the same bass is F♯m7. One fret on the second string separates them, which is a great deal less effort than the difference between the two symbols suggests.

Rooted on the fifth string, x 9 10 9 10 x puts one of each note under the hand at the ninth fret. For comping, x x 4 5 5 5 is the easiest voicing on the neck: index on the fourth string at the fourth fret and one finger laid flat across the top three at the fifth. Nothing stretches, nothing is doubled, and it sits exactly where a guitarist playing in E minor already has a hand.

Inversions

The second inversion is more useful than it looks. With C in the bass the tritone turns over, C up to F♯, and the root is buried in the middle of the chord, so the harmony passes instead of announcing itself. Put D underneath those same four notes and they become D9, which is how a pianist plays a ninth chord while leaving the root to somebody else. Chord Inversions and Voice Leading explains why the lowest voice makes the decision.

Voicings

Which Keys Contain F♯m7♭5

• viiø of G major
• iiø of E natural minor
• iiø of E harmonic minor
• viiø of G melodic minor
• viø of A melodic minor
• viø of A dorian

The first three are one key signature wearing three hats. What separates them is a note this chord does not contain: E natural minor has D, E harmonic minor raises it to D♯, and the chord sits on the second degree of both without caring. That indifference is the point. The same fingering serves whether the dominant after it is a plain Bm or a B7, so a player can commit to the ii before deciding how hard the V is going to push.

The A dorian entry is the one place on the list where the chord is a colour rather than a function, sounding over an A drone.

Where F♯m7♭5 Shows Up

The third row is the one most players learn by accident. Autumn Leaves, taken into E minor as guitarists usually take it, runs a cycle of fourths through G major and then turns the corner into its relative minor using precisely these two chords. Anybody who has played that tune has played this chord, whether or not they could name it, and it is where the shape at the fourth and fifth frets gets drilled into the hand.

Its other job is quieter. As the vii of G major it is the diatonic seventh chord on the leading note, borrowed from nowhere, and it slips between chords rather than announcing anything.

Once the shape is under the fingers, the cheap move is to slide it. Take x x 4 5 5 5 up three frets to x x 7 8 8 8 and you have Am7♭5, up three more for Cm7♭5, and each of them is the ii of a different minor key. The half-diminished chord is where a guitarist learns that a minor cadence is portable.

Related Chords

• F♯ Diminished Chord the triad underneath this one
• F♯ Minor 7th Chord C♯ in place of C, and the tension goes
• A Minor 6th Chord the same four notes with A in the bass
• F♯ Minor Chord the plain minor triad on this root
• Seventh Chords: The Complete Guide

Learn More

• The ii, V, I Progression in Practice
• Diatonic Chords: A Beginner’s Guide
• Extended Chords and Jazz Harmony
• The Circle of Fifths Explained
• The E Natural Minor Scale, the key that gives this chord its work