Pick a root, choose a quality, and read off the chord's notes, intervals, MIDI numbers, semitone formula, and inversions — with a piano visualization and Web Audio playback.
A chord is a stack of notes built from a root using a pattern of semitone intervals. A major triad is 0–4–7 (root, major 3rd, perfect 5th); a minor triad is 0–3–7; a dominant 7th adds a minor 7th at 10. Inversions move the lowest note up an octave: in 1st inversion the 3rd is the bass, in 2nd inversion the 5th is the bass. MIDI numbers identify each pitch as an integer (middle C = 60), and the frequency in Hz follows f = 440 × 2^((midi−69)/12).