Learn to play 17 types of piano chords using 12 different root notes with this 34-page PDF! Chords are sorted both by their root note (C, D, E, etc.) and type (major, minor, augmented, diminished, etc.).
But to summarize, augmented chords are built using a “1 – 3 – 5” pattern on the piano: a root, major third, and an augmented fifth. Since the root of this chord is B, a fifth up from B alphabetically is an F, so we need to label this note as a type of F. This is why it’s called “F♯♯”.
You can use this pattern to build any augmented chord on the piano. Start with a major chord, then raise the upper note 1/2 step.
Another way to label augmented chords is with the “+” symbol. So an augmented chord could be written as either Baug, or B+.