Diminished piano chords are not the most common type of chord but they do add something interesting to a chord progression when needed.
Here I'll explain both how diminished chords are made and also provide a (pinable) list of all the diminished chords.
Diminished chords are made this way: start with a major chord. For example, C major – C E G. To make it diminished you lower the 3rd and 5th notes of the scale. In our example’s case, that would be the C major scale.
Lowering a note means to make it lower by a semi-tone or half-step. This usually means going from a white key to the next lowest black key or vice versa. For example, E goes to Eb, C# goes to C. Be careful of C and F though because with these notes you go to the next lowest white key.
To make a C diminished chord, you must lower E to Eb and G to Gb. Altogether, the chord is C Eb Gb. A diminished chord is written like this: Cdim or Co (with the "o" being set up high in line with the top of the C, not low like you see here).
Here’s a list of the diminished chords:
Some of these chords have double flats. That means that you take the note that already is a flat, and make it lower by an additional semi-tone. For example, Bbb (double flat) will actually be an A on the piano.
Diminished chords are not very common. If you need to know a specific chord, just remember to lower the 3rd and 5th notes. You can also go and find the specific chord when you come across it.
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If you want to learn more about chords and how to make the different kinds, check out the chord theory page.
You can also find more chords on the
chord charts page. This is about all there is to diminished piano chords. They sound complicated but once you understand them, they’re easy!