Cdim7 on the ukulele is a diminished 7th chord made from C, D#, F#, A. Its first ukulele voicing is the movable voicing: G string at fret 5 (ring finger); C string at fret 3 (middle finger); E string at fret 2 (index finger); A string open. Below you will find its notes and intervals, every usable voicing on the ukulele, the common mistakes players make with it and the keys and progressions where it belongs.
What notes are in the Cdim7 chord?
The Cdim7 chord is a diminished 7th chord, and its notes are fixed: C, D#, F#, A. 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 Cdim7 at a glance. On the ukulele, start with the first voicing above and listen for the notes C, D#, F#, A in Cdim7.
| Note | Interval |
|---|---|
| C | Root |
| D# | b3 |
| F# | b5 |
| A | 6 |
The root is C, the note the chord is named after and the note your ear hears as home. Above it, the intervals in Cdim7 are b3, b5, 6. That combination is what makes Cdim7 sound the way it does: the intervals decide the colour, and the root decides the pitch. On the ukulele, the notes appear in the order the fingering dictates, but the set of notes never changes.
Cdim7 sounds tense, dark and symmetrical — the diminished 7th chord divides the octave into four equal parts and sounds like it belongs nowhere. 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 ukulele, the movable voicing voicing is the place to hear it in Cdim7.
Comparing Cdim7 with its closest relatives helps to fix it in your ear. In short, diminished 7th against half-diminished: Cdim7 flattens the 7th twice, to A; the half-diminished chord keeps the flattened 7th A#. That one note changes the whole character. Play both chords slowly, one after the other, and notice which note moves. Naming that note out loud while you play is the fastest way to learn the difference. On the ukulele, start with the first voicing above and listen for the notes C, D#, F#, A in Cdim7.
How to play Cdim7 on ukulele
On the ukulele, Cdim7 has 3 voicings in the data below, and each one uses the same notes — C, D#, F#, A — in a different place on the neck. There are 3 voicings listed for Cdim7 on the ukulele; 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.
Another way to play Cdim7 is the movable voicing, in around fret 2: G string at fret 5 (ring finger); C string at fret 3 (middle finger); E string at fret 2 (index finger); A string open. The stretch is the challenge: the fretted notes span from fret 2 to fret 5, so keep your thumb low behind the neck and let your fingers reach rather than squeezing the neck. Strum or pluck it slowly first and check that every note in Cdim7 — C, D#, F#, A — sounds, with no buzz and no accidental open string.
The barre chord is the voicing to learn if you want Cdim7 in around fret 1: G string at fret 2 (index finger); C string at fret 3 (middle finger); E string at fret 2 (index finger); A string at fret 3 (ring finger). It barres across strings 1 to 3 at fret 2 with the index finger. The barre is the hard part: the index finger must press every string from 1 to 3 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 Cdim7 — C, D#, F#, A — sounds, with no buzz and no accidental open string.
The barre chord puts Cdim7 in around fret 5: G string at fret 5 (index finger); C string at fret 6 (middle finger); E string at fret 5 (index finger); A string at fret 6 (ring finger). It barres across strings 1 to 3 at fret 5 with the index finger. The barre is the hard part: the index finger must press every string from 1 to 3 evenly at fret 5, 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 Cdim7 — C, D#, F#, A — sounds, with no buzz and no accidental open string.
Choosing between the voicings of Cdim7 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 Cdim7 up the neck to any key without changing the shape. When you change chords, pick the voicing of Cdim7 that sits closest to the chord before it — shorter moves between shapes mean faster, cleaner changes. Practise the change into Cdim7 from the chord that comes before it in your song, not the chord on its own, because the move is the skill. On the ukulele, start with the first voicing above and listen for the notes C, D#, F#, A in Cdim7.
A short practice routine for Cdim7 on the ukulele: 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 Ukulele Chord Finder to see the diagram for Cdim7 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 Cdim7 sound wrong on the ukulele, 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. Four notes a minor 3rd apart sound muddy in low octaves. Spread them out or use a higher voicing. On the ukulele, the movable voicing voicing is the place to hear it in Cdim7.
Forgetting it is symmetrical. Because the notes are evenly spaced, Cdim7 can resolve in four directions. Practise resolving it to the tonic and to the chord a semitone above its root. On the ukulele, the movable voicing voicing is the place to hear it in Cdim7.
Pressing too hard on the nylon strings. Ukulele strings need far less pressure than guitar strings, and pressing hard on Cdim7 pulls the notes sharp and tires the hand. Use the lightest touch that gives a clean note, and keep your fingers close to the frets. On the ukulele, the movable voicing of Cdim7 puts those notes under your fingers in the order the fingering lists them.
Playing the wrong 7th. The 7th here is A, a double-flattened 7th. Play A# and you have the half-diminished chord instead. On the ukulele, start with the first voicing above and listen for the notes C, D#, F#, A in Cdim7.
Where Cdim7 is used
Cdim7 is not a diatonic triad in any major or minor key, because it is an extended or altered chord, but its base triad belongs to the key of D# major, the key of G# major, the key of A# major. a chromatic connector between two chords a whole step apart. As a dominant-type chord it also points toward F major, the key a perfect fourth above C, which is the tonic it most often resolves to. That is where Cdim7 does its work: not as a home chord, but as a chord that creates movement and then resolves. On the ukulele, the movable voicing of Cdim7 puts those notes under your fingers in the order the fingering lists them.
Because Cdim7 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 Cdim7 in a progression in any key and hear how it connects to the chords around it. On the ukulele, start with the first voicing above and listen for the notes C, D#, F#, A in Cdim7.
The same chord on other instruments is covered in Cdim7 on guitar, Cdim7 on piano, Cdim7 on bass, and the scales that fit over it are the C major scale and the C minor pentatonic scale. Learning Cdim7 on the ukulele and then checking it on another instrument is one of the best ways to fix the notes — C, D#, F#, A — in your memory, because the notes stay the same while everything else changes.
Practising Cdim7
A short worked example makes Cdim7 concrete. Play the four-chord progression F – C – Dm – A# in F major, the key Cdim7 most often resolves toward: F – C – Dm – A#. Play each chord for one bar at a slow tempo, and listen to how Cdim7 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 Cdim7 itself, and notice how its character changes when it opens the progression instead of sitting inside it. On the ukulele, start with the first voicing above and listen for the notes C, D#, F#, A in Cdim7.
For a second exercise, play Cdim7 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 Cdim7 is built for when it acts as a dominant. Finish by playing Cdim7 on its own, slowly, and naming each note out loud as you play it: C, D#, F#, A. 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 ukulele, the movable voicing of Cdim7 puts those notes under your fingers in the order the fingering lists them.
Frequently asked questions
What is the easiest voicing of Cdim7 on the ukulele?
The movable voicing is the easiest voicing listed for Cdim7 on the ukulele: frets 5–3–2–0, fingers 3–2–1–0. Learn that shape first, get every note ringing cleanly, and only then move on to the alternative voicings further up the neck.
What notes are in Cdim7?
Cdim7 contains C, D#, F#, A: root C, minor 3rd D#, diminished 5th F# and diminished 7th A. The notes are all a minor 3rd apart, which is what makes the chord symmetrical. On the ukulele, the voicings above put that note under your fingers.
Why does Cdim7 sound so tense?
Every interval in it is a minor 3rd, and the chord contains two tritones. There is no stable note to rest on, so the ear hears it as a chord that must move. On the ukulele, the voicings above put that note under your fingers.
Where is Cdim7 used?
As a passing chord between two chords a whole step apart, as a dominant substitute, and as the vii°7 chord in harmonic minor. It is a brief, dramatic colour, not a chord to sit on. On the ukulele, the voicings above put that note under your fingers.
How do you play Cdim7 on the ukulele?
The first voicing is the movable voicing: frets 5–3–2–0, fingers 3–2–1–0, on the ukulele. That voicing uses the notes C, D#, F#, A, and it is the one to learn first. The page above lists more voicings for Cdim7, so you can choose the shape nearest the chords around it.