The Cdim guitar chord is built from the notes C, D#, F#. Its first guitar voicing is the movable voicing: low E string muted; A string at fret 3 (middle finger); D string at fret 4 (ring finger); G string at fret 5 (little finger); B string at fret 4 (little finger); high e string at fret 2 (index finger). It is a diminished chord, and this page gives you its exact notes, the fingerings that work on the guitar, the mistakes to avoid and the progressions it appears in.
What notes are in the Cdim chord?
The Cdim chord is a diminished chord, and its notes are fixed: C, D#, F#. 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 C, so you can see the structure of Cdim at a glance. On the guitar, start with the first voicing above and listen for the notes C, D#, F# in Cdim.
| Note | Interval |
|---|---|
| C | Root |
| D# | b3 |
| F# | b5 |
The root is C, the note the chord is named after and the note your ear hears as home. Above it, the intervals in Cdim are b3, b5. Once you know the intervals, you can build Cdim from any root by counting the same semitone steps, which is how the chord works in every key. On the guitar, the notes appear in the order the fingering dictates, but the set of notes never changes.
Cdim sounds eerie and compressed, a chord built from two minor 3rds stacked on each other. The colour is strongest when all the notes ring clearly. A muted chord tone, especially the 3rd or the 7th where the chord has one, flattens the character of Cdim noticeably. On the guitar, start with the first voicing above and listen for the notes C, D#, F# in Cdim.
Comparing Cdim with its closest relatives helps to fix it in your ear. In short, diminished against minor: both have the minor 3rd D#, but Cdim flattens the 5th to F# where the minor chord keeps the perfect 5th G. Practise the two chords back to back and listen to the one note that changes — that single note is the difference between the two chords. On the guitar, the movable voicing voicing is the place to hear it in Cdim.
How to play Cdim on guitar
On the guitar, Cdim has 3 voicings in the data below, and each one uses the same notes — C, D#, F# — in a different place on the neck. The first voicing below is the one to learn first, and the alternatives cover the rest of the neck. 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 movable voicing puts Cdim in around fret 2: low E string muted; A string at fret 3 (middle finger); D string at fret 4 (ring finger); G string at fret 5 (little finger); B string at fret 4 (little finger); high e string at fret 2 (index finger). The challenge here is the muted string: 1 string is marked x, and it needs to stay silent. Let the edge of a fretting finger rest lightly on it — muting by touch, not by pressing. Strum or pluck it slowly first and check that every note in Cdim — C, D#, F# — sounds, with no buzz and no accidental open string.
The barre chord is the voicing to learn if you want Cdim in around fret 2: low E string at fret 2 (index finger); A string at fret 3 (middle finger); D string at fret 4 (ring finger); G string at fret 5 (little finger); B string at fret 4 (little finger); high e string at fret 2 (index finger). It barres across strings 1 to 6 at fret 2 with the index finger. The barre is the hard part: the index finger must press every string from 1 to 6 evenly at fret 2, 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 Cdim — C, D#, F# — sounds, with no buzz and no accidental open string.
The open position is the voicing to learn if you want Cdim in open position: low E string muted; A string at fret 3 (little finger); D string at fret 1 (index finger); G string muted; B string at fret 1 (middle finger); high e string at fret 2 (ring finger). The challenge here is the muted strings: 2 strings are marked x, and they need to stay silent. Let the edge of a fretting finger rest lightly on them — muting by touch, not by pressing. Strum or pluck it slowly first and check that every note in Cdim — C, D#, F# — sounds, with no buzz and no accidental open string.
Choosing between the voicings of Cdim 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 Cdim up the neck to any key without changing the shape. When you change chords, pick the voicing of Cdim that sits closest to the chord before it — shorter moves between shapes mean faster, cleaner changes. Practise the change into Cdim 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 movable voicing of Cdim puts those notes under your fingers in the order the fingering lists them.
A short practice routine for Cdim on the guitar: play the first voicing four times slowly, checking each note, then change to it from the chord a fourth above C 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 Cdim 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 Cdim 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.
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 movable voicing of Cdim puts those notes under your fingers in the order the fingering lists them.
Confusing it with the half-diminished 7th. The half-diminished chord adds a flattened 7th to this triad. Cdim on its own has only three notes: C, D#, F#. On the guitar, the movable voicing voicing is the place to hear it in Cdim.
Barre collapsing on the high strings. In a barre voicing of Cdim, the high strings are the ones that buzz first, because the index finger presses hardest near the thumb. If the top notes of Cdim sound dead, roll the barring finger slightly toward the fret and press from the arm, not from squeezing the neck. On the guitar, the movable voicing of Cdim puts those notes under your fingers in the order the fingering lists them.
Playing a perfect 5th. If the 5th is G instead of F#, the chord is minor, not diminished. The flattened 5th is the note that defines this chord. On the guitar, the movable voicing voicing is the place to hear it in Cdim.
Where Cdim is used
As a diatonic chord, Cdim belongs to the key of C# major, the key of A# 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. a passing chord between two diatonic chords, often used to add chromatic movement. 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, start with the first voicing above and listen for the notes C, D#, F# in Cdim.
Because Cdim 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 C 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 Cdim in a progression in any key and hear how it connects to the chords around it. On the guitar, the movable voicing voicing is the place to hear it in Cdim.
The same chord on other instruments is covered in Cdim on piano, Cdim on ukulele, Cdim on bass, and the scales that fit over it are the C major scale and the C minor pentatonic scale. Learning Cdim on the guitar and then checking it on another instrument is one of the best ways to fix the notes — C, D#, F# — in your memory, because the notes stay the same while everything else changes.
Practising Cdim
A short worked example makes Cdim concrete. Play the four-chord progression C# – G# – A#m – F# in C# major, where Cdim is diatonic: C# – G# – A#m – F#. Play each chord for one bar at a slow tempo, and listen to how Cdim 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 Cdim itself, and notice how its character changes when it opens the progression instead of sitting inside it. On the guitar, the movable voicing of Cdim puts those notes under your fingers in the order the fingering lists them.
For a second exercise, play Cdim and then the chord a fourth above C, 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 Cdim is built for when it acts as a dominant. Finish by playing Cdim on its own, slowly, and naming each note out loud as you play it: C, D#, F#. 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 movable voicing voicing is the place to hear it in Cdim.
Frequently asked questions
What notes are in Cdim?
Cdim contains C, D#, F#: the root C, the minor 3rd D# and the diminished 5th F#. It is two minor 3rds stacked — C to D#, then D# to F#. On the guitar, the voicings above put that note under your fingers.
Where is Cdim 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 voicings above put that note under your fingers.
How do you play Cdim on the guitar?
The first voicing is the movable voicing: frets x–3–4–5–4–2, fingers 0–2–3–4–4–1, on the guitar. That voicing uses the notes C, D#, F#, and it is the one to learn first. The page above lists more voicings for Cdim, so you can choose the shape nearest the chords around it.
Is Cdim hard to play on the guitar?
It depends on the voicing. The first voicing of Cdim 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 Cdim on the guitar?
The movable voicing is the easiest voicing listed for Cdim on the guitar: frets x–3–4–5–4–2, fingers 0–2–3–4–4–1. Learn that shape first, get every note ringing cleanly, and only then move on to the alternative voicings further up the neck.