Cdim7 chord on guitar

Cdim7 is C, E♭, G♭ and B𝄫. The usual shape is x-3-4-2-4-x. Play it once at full speed, then at a quarter to hear every note.

x-3-4-2-4-x · movable · medium

Notes: C · E♭ · G♭ · B𝄫
Formula: 1 · ♭3 · ♭5 · ♭♭7
First shape: x-3-4-2-4-x

How to play Cdim7 on guitar

Shape 1, x-3-4-2-4-x, reading from the low E string on the left, starts at the 2nd fret:

Put your index finger on the G string at the 2nd fret, which is B𝄫.
Put your middle finger on the A string at the 3rd fret, which is C.
Put your ring finger on the D string at the 4th fret, which is G♭.
Put your pinky finger on the B string at the 4th fret, which is E♭.
Mute the low E and high E strings with the side of a finger so they don't ring.

This shape uses your pinky. It feels weak at first; press with the tip and let the finger stay curved.
Aim the strum at the thinner strings only; the lower ones are marked × for a reason.

Other ways to play Cdim7

8-x-7-8-7-x: movable shape at the 7th fret, medium. Built on the Edim7 open shape with the barre as a movable nut; the root is on the 6th string.
x-x-10-11-10-11: movable shape at the 10th fret, medium. Only the thinner strings sound, which cuts through a band without getting muddy.
x-15-13-14-13-14: partial barre shape at the 13th fret, medium. Higher up the neck it sounds brighter; handy when another guitar is already playing a lower shape.

Moving between Cdim7 and its neighbours

The chords Cdim7 usually goes to, and what changes under your fingers.

C♯ (leads up a half step): Cdim7 (x-3-4-2-4-x) to C♯ (x-4-6-6-6-4): the index finger lays across the A to high E strings at the 4th fret, your middle finger lands on the D string, 6th fret, move the ring finger to the G string, 6th fret. Nothing carries over, so drill it slowly, lifting and landing all fingers at once. C♯ on guitar
C♯m (leads up a half step): Cdim7 (x-3-4-2-4-x) to C♯m (x-4-6-6-5-4): the index finger lays across the A to high E strings at the 4th fret, the middle finger goes to the B string, 5th fret, your ring finger lands on the D string, 6th fret. No finger can stay, so practice lifting all of them together and landing the new shape as a unit. C♯m on guitar
F (a fifth down): Cdim7 (x-3-4-2-4-x) to F (1-3-3-2-1-1): the index finger lays across the low E to high E strings at the 1st fret, the middle finger goes to the G string, 2nd fret, your ring finger lands on the A string, 3rd fret. Nothing carries over, so drill it slowly, lifting and landing all fingers at once. Listen for C and B𝄫, which stay put while the rest moves. F on guitar

Cdim7 is a diminished seventh: three minor thirds stacked, so the chord divides the octave into four equal parts. Cdim7 can stand in for a dominant seventh a half step below, which is why it links chords so smoothly. Play it once strummed and once picked to hear the difference.

A short Cdim7 drill

Before strumming, play x-3-4-2-4-x note by note: C then G♭ then B𝄫 then E♭. A dead note tells you exactly which finger to fix. Then switch to 8-x-7-8-7-x and back four times without looking at your hand.

Where Cdim7 shows up

Cdim7 on piano and ukulele

Switching instruments? Try Cdim7 on ukulele or Cdim7 on piano, or compare them on the Cdim7 chord page.

Related C chords on guitar

Other diminished seventh chords

Cdim7 on guitar: questions

What notes are in Cdim7 on guitar?

C, E♭, G♭ and B𝄫. In the x-3-4-2-4-x shape the strings play C (A string), G♭ (D string), B𝄫 (G string) and E♭ (B string).

What's the easiest way to play Cdim7 on guitar?

In standard tuning Cdim7 can't use open strings. Begin with x-3-4-2-4-x. It uses 4 fingers and no barre, and in many songs a capo can take over part of the work.

Is Cdim7 a barre chord on guitar?

Not the usual shape: x-3-4-2-4-x needs no barre.

Which string does Cdim7 start on?

In the x-3-4-2-4-x shape the lowest string you play is the A string at the 3rd fret, which is C, the root. Skip the low E and high E strings.

Checked automatically: no shape here plays a note outside Cdim7. Updated September 2026.