To play Fdim on the guitar, you need the notes F, G#, B. Its first guitar voicing is the open position: low E string at fret 1 (index finger); A string at fret 2 (little finger); D string at fret 3 (little finger); G string at fret 1 (middle finger); B string open; high e string at fret 1 (ring finger). This guide covers the diminished chord in full: what is in it, how to play it cleanly on the guitar, where it fits musically and how to practise it.
What notes are in the Fdim chord?
The Fdim chord is a diminished chord, and its notes are fixed: F, G#, B. Every voicing on every instrument uses these same notes, in some order and in some octave — change one of them and you are playing a different chord. The table below lists each note with its interval from the root F, so you can see the structure of Fdim at a glance. On the guitar, start with the first voicing above and listen for the notes F, G#, B in Fdim.
| Note | Interval |
|---|---|
| F | Root |
| G# | b3 |
| B | b5 |
The root is F, the note the chord is named after and the note your ear hears as home. Above it, the intervals in Fdim are b3, b5. Learn those intervals rather than memorising the shape alone, because the same interval pattern transposed to another root gives you the same quality of chord anywhere. On the guitar, the notes appear in the order the fingering dictates, but the set of notes never changes.
Fdim sounds restless and chromatic, the sound of a chord that is really a passing chord in disguise. That character comes straight from the intervals above, not from the instrument: the same notes on piano, guitar or ukulele carry the same colour, even though the voicing changes. On the guitar, the open position of Fdim puts those notes under your fingers in the order the fingering lists them.
Comparing Fdim with its closest relatives helps to fix it in your ear. In short, diminished against minor: both have the minor 3rd G#, but Fdim flattens the 5th to B where the minor chord keeps the perfect 5th C. Hearing the comparison matters more than reading it: play Fdim, then play the chord it is compared with above, and let your ear find the note that changed. On the guitar, start with the first voicing above and listen for the notes F, G#, B in Fdim.
How to play Fdim on guitar
On the guitar, Fdim has 3 voicings in the data below, and each one uses the same notes — F, G#, B — in a different place on the neck. There are 3 voicings listed for Fdim on the guitar; learn the first, then add the others as you need them. Finger numbers below use 1 for the index finger, 2 for the middle finger, 3 for the ring finger and 4 for the little finger, and x means the string is not played.
The open position is the voicing to learn if you want Fdim in open position: low E string at fret 1 (index finger); A string at fret 2 (little finger); D string at fret 3 (little finger); G string at fret 1 (middle finger); B string open; high e string at fret 1 (ring finger). This voicing is comfortable because the fretted notes sit close together, from fret 1 to fret 3, so your hand stays relaxed and every note can ring. Strum or pluck it slowly first and check that every note in Fdim — F, G#, B — sounds, with no buzz and no accidental open string.
The barre chord is the voicing to learn if you want Fdim in open position: low E string at fret 1 (index finger); A string at fret 2 (middle finger); D string at fret 3 (ring finger); G string at fret 1 (index finger); B string open; high e string at fret 4 (little finger). It barres across strings 1 to 4 at fret 1 with the index finger. The barre is the hard part: the index finger must press every string from 1 to 4 evenly at fret 1, so roll it slightly onto its bony side and keep it close to the fret wire. If the barre buzzes, move it a fraction closer to the fret and press from the arm, not the thumb alone. Strum or pluck it slowly first and check that every note in Fdim — F, G#, B — sounds, with no buzz and no accidental open string.
The movable voicing puts Fdim in around fret 2: low E string at fret 4 (ring finger); A string at fret 2 (index finger); D string at fret 3 (middle finger); G string at fret 4 (little finger); B string open; high e string at fret 4 (little finger). This voicing is comfortable because the fretted notes sit close together, from fret 2 to fret 4, so your hand stays relaxed and every note can ring. Strum or pluck it slowly first and check that every note in Fdim — F, G#, B — sounds, with no buzz and no accidental open string.
Choosing between the voicings of Fdim is a musical decision, not a right-or-wrong one. The open or low-position voicing rings the most and suits strumming, while a barre or movable voicing lets you slide Fdim up the neck to any key without changing the shape. When you change chords, pick the voicing of Fdim that sits closest to the chord before it — shorter moves between shapes mean faster, cleaner changes. Practise the change into Fdim from the chord that comes before it in your song, not the chord on its own, because the move is the skill. On the guitar, the open position of Fdim puts those notes under your fingers in the order the fingering lists them.
A short practice routine for Fdim on the guitar: play the first voicing four times slowly, checking each note, then change to it from the chord a fourth above F and back, four times, at a slow tempo. Then play the second voicing the same way. If a note buzzes, stop and fix the finger placement rather than playing through the buzz — clean notes at a slow tempo become clean notes at full tempo, while buzzes practised fast become habits. Use the Guitar Chord Finder to see the diagram for Fdim while you practise, and the Chord Finder to compare it with the same chord on other instruments.
Common mistakes
These are the mistakes that most often make Fdim sound wrong on the guitar, and each one has a concrete fix. Work through them one at a time rather than trying to fix everything at once.
Using it as a home chord. Fdim is unstable by design. It wants to resolve, usually up to the tonic. Do not end a phrase on it unless you mean to leave the listener hanging. On the guitar, the open position of Fdim puts those notes under your fingers in the order the fingering lists them.
Voicing it too low. A diminished triad low down sounds muddy because its notes are close together. Use a higher voicing or spread the notes across octaves. On the guitar, the open position voicing is the place to hear it in Fdim.
Confusing it with the half-diminished 7th. The half-diminished chord adds a flattened 7th to this triad. Fdim on its own has only three notes: F, G#, B. On the guitar, start with the first voicing above and listen for the notes F, G#, B in Fdim.
Barre collapsing on the high strings. In a barre voicing of Fdim, the high strings are the ones that buzz first, because the index finger presses hardest near the thumb. If the top notes of Fdim sound dead, roll the barring finger slightly toward the fret and press from the arm, not from squeezing the neck. On the guitar, the open position of Fdim puts those notes under your fingers in the order the fingering lists them.
Where Fdim is used
As a diatonic chord, Fdim belongs to the key of F# major, the key of D# minor. In those keys it is one of the seven chords built from the key's own notes, so it fits without any chromatic notes. the vii° chord in major keys, leading straight to the tonic. That is the practical meaning of belonging to a key: the chord sounds settled there, and the other chords of the key lead to it and away from it naturally. On the guitar, the open position voicing is the place to hear it in Fdim.
Because Fdim is an extended or altered chord, it appears in progressions as a colour or a dominant rather than as a diatonic staple. Try it in place of the plain F triad in a progression you already know, and listen to how the extra notes change the feel — that substitution is the usual way extended chords enter real music. The Chord Progression Builder lets you try Fdim in a progression in any key and hear how it connects to the chords around it. On the guitar, the open position voicing is the place to hear it in Fdim.
The same chord on other instruments is covered in Fdim on piano, Fdim on ukulele, Fdim on bass, and the scales that fit over it are the F major scale and the F minor pentatonic scale. Learning Fdim on the guitar and then checking it on another instrument is one of the best ways to fix the notes — F, G#, B — in your memory, because the notes stay the same while everything else changes.
Practising Fdim
A short worked example makes Fdim concrete. Play the four-chord progression F# – C# – D#m – B in F# major, where Fdim is diatonic: F# – C# – D#m – B. Play each chord for one bar at a slow tempo, and listen to how Fdim sounds in that sequence — whether it feels like home, like a lift, or like a chord on its way somewhere else. Then play the same four chords in a different order, starting on Fdim itself, and notice how its character changes when it opens the progression instead of sitting inside it. On the guitar, the open position of Fdim puts those notes under your fingers in the order the fingering lists them.
For a second exercise, play Fdim and then the chord a fourth above F, back and forth, four times each. That move — a chord and the chord a fourth above it — is the most common resolution in Western music, and it is the move Fdim is built for when it acts as a dominant. Finish by playing Fdim on its own, slowly, and naming each note out loud as you play it: F, G#, B. Naming the notes while you play them is what turns a shape into knowledge you can use in any key. Test yourself with the Practice Chord Quiz and keep time with the Metronome as the tempo rises. On the guitar, the open position of Fdim puts those notes under your fingers in the order the fingering lists them.
Frequently asked questions
What notes are in Fdim?
Fdim contains F, G#, B: the root F, the minor 3rd G# and the diminished 5th B. It is two minor 3rds stacked — F to G#, then G# to B. On the guitar, the first voicing above shows where that note sits.
Where is Fdim used?
Most often as the vii° chord in a major key, leading to the tonic, and as a passing chord between two chords a whole step apart. It also substitutes for a dominant 7th chord. On the guitar, the first voicing above shows where that note sits.
How do you play Fdim on the guitar?
The first voicing is the open position: frets 1–2–3–1–0–1, fingers 1–4–4–2–0–3, on the guitar. That voicing uses the notes F, G#, B, and it is the one to learn first. The page above lists more voicings for Fdim, so you can choose the shape nearest the chords around it.
Is Fdim hard to play on the guitar?
It depends on the voicing. The first voicing of Fdim on the guitar is the easiest starting point, and the movable voicings further up the neck are harder because they need a barre or a wider stretch. Practise the first voicing cleanly at a slow tempo before you try the others, and the harder shapes will come more easily.
What is the easiest voicing of Fdim on the guitar?
The open position is the easiest voicing listed for Fdim on the guitar: frets 1–2–3–1–0–1, fingers 1–4–4–2–0–3. Learn that shape first, get every note ringing cleanly, and only then move on to the alternative voicings further up the neck.