How to Play Augmented and Diminished Chords on the Piano or Keyboard
In addition to major and minor chords, piano and keyboard players should be familiar with augmented and diminished chords. Major and minor chords differ from each other only in the third interval. The top note, the fifth interval, is the same for both types of chords. So, by altering the fifth interval of a major or minor chord, you can create two new chord types, both triads.
An augmented chord contains a root note, a major third (M3) interval, and an augmented fifth (aug5), which is a perfect fifth (P5) raised one half step. Think of an augmented chord as simply a major chord with the top note raised one half step.
When writing the chord symbol, the suffixes for augmented chords include +, aug, and ♯5. One advantage of ♯5 is that it actually tells you what to do to change the chord — you sharp the fifth.
A diminished chord contains a root note, a minor third (m3) interval, and a diminished fifth (dim5), which is a perfect fifth (P5) interval lowered one half step.
Note the suffix used to signal a diminished chord in the chord symbol: dim. You may also see the suffix dim in the chord symbol, as in Fdim.
You may find it easiest to use fingers 1, 2, and 4 for augmented and diminished chords played with the right hand. For the left, try 5, 3, and 2.
Here’s an example of how you may encounter diminished and augmented chords in a song. The melody is the last phrase of Stephen Foster’s “Old Folks at Home.” Take these new chords for a spin and see how they subtly affect a song’s harmony.