In response to popular demand, key-notes is happy to add Free Piano Chords to its growing list of free resources. (It should go without saying that these and any other piano chord diagrams should be used only as a temporary aid to learning music theory and for occasional reference, not as cheat sheets!)
The Free Piano Chord Chart contains the major, minor, diminished and augmented triads, as well as dominant, diminished, minor and major seventh chords.
The chart of Advanced Piano Chords consists of major and minor triads with added sixths, suspended 4 and 2, dominant seventh with suspended 4, minor-major seventh, half-diminished seventh and ninth chords.
While printable chord charts for piano are handy to the intermediate student and for occasional reference, it's important not to have to rely on them. It's vital instead to understand how each chord is constructed, which is really quite simple: All common chords are built on thirds, and those thirds are either major or minor. Thus, to use the simplest example, a major chord (starting from the bottom) consists simply of a major third, then a minor third on top of that, whereas a minor chord is the reverse. Seventh and ninth chords simply stack additional thirds on top.
A useful strategy for learning chords is to write out all chords by hand. Once you've done it once or twice you'll almost never need to refer to our free piano chords charts again!