Three notes · 1 ♭3 ♭5 · pure 5:6:7
The diminished chord
A diminished chord is two minor thirds stacked: a root, a minor third, and a diminished fifth 6 semitones up. It sounds tense and restless, and it nearly always moves on to another chord.
How it's built
It's a minor chord with the fifth lowered a semitone: C, E♭ and G♭. The outside interval, root to ♭5, is the tritone, exactly half an octave on a piano and one of the most unsettled intervals in common harmony. It's written G♭ rather than F♯ because it's still the fifth of C, only lowered.
Singing it in tune
Switched to Pure, this page tunes it 5:6:7. The minor third sits 15.6 cents (a cent is a hundredth of a semitone) above the piano's, and the diminished fifth, 7:5, 17.5 cents below the piano's tritone. That leaves a small minor third between the top two notes, 7:6, which is 33.1 cents narrower than the piano's. So when it's tuned pure, the two thirds the chord is built from aren't the same size.
Those are the ratios of the top three notes of a barbershop seventh, 4:5:6:7. That's no accident: B, D and F are the top of G7, G, B, D and F, and a diminished chord often does the job of a dominant 7th with its root left out.
Where you hear it
In a major key it's the chord on the seventh note: B, D and F in C, which pulls strongly to C. In a minor key it sits on the second note, often just before the dominant. It also works as a passing chord between two chords a step apart, and in choral writing it's often found in first inversion, with its third at the bottom.
More chord types
Free tools by Stackapella
All of these are free, and so is every course.
Stackapella teaches you to sing harmony one part at a time, right in your browser.
- A guide sings your partHear your line over the others, slow it down, then take your turn.
- Your notes light upEach note shows where you landed, and a hint when to go up or down.
- Record every part yourselfStack your takes in time until you're the whole choir.
- Every course free
- Open source
- No ads, no tracking
Questions
What notes are in a C diminished chord?
C, E♭ and G♭. The one that belongs to the key of C major is B diminished: B, D and F.
Why is it called diminished?
Because its fifth is diminished: a semitone smaller than the perfect fifth of a major or minor chord.
What is the difference between a diminished and a diminished 7th chord?
A diminished chord has three notes, and a diminished 7th adds a fourth: one more minor third on top, 9 semitones above the root. Add a minor seventh instead, 10 semitones up, and you have the half-diminished chord.
What does the ° symbol mean?
Diminished: C° is the same as Cdim. C°7 is the diminished 7th, and a circle with a slash, Cø7, is half-diminished.
More free tools
No account, no ads. Each one keeps working offline once you've opened it.
See all 17 tools