Bb Augmented Chord

The root is B flat, the major third is D, and the augmented fifth is F sharp. The spelling is B flat-D-F sharp, formula 1-3-sharp 5. F sharp is the raised fifth. Compare it with the ordinary fifth of B flat major on the neighboring key. Both gaps inside the chord are major thirds, or four semitones each.

The symbol may be written B flataug or B flat+. The plus sign means the fifth is raised. It does not ask you to add an extra note to a normal major triad. Augmented Chord explains the pattern from other roots.

Move the lowest note up an octave at each step:

The three notes remain the same in every position. Because each neighboring gap is a major third, the shape can feel unusually even as you rotate it. The written root still depends on how the chord is spelled and used in the music; Chord Inversions shows how the bass position is marked.

Play the Bb Major Chord and then the augmented triad without changing the root or third. Only the fifth moves up one semitone. Return to the major triad and listen for the familiar perfect fifth coming back. This is a more reliable test than calling the augmented sound simply “mysterious.”

Not by itself. Its evenly spaced notes do not provide the same clear root-and-fifth anchor as a major triad. In a passage, a moving melody or bass can give it direction. Try holding B flat in the bass while moving F sharp up and down by one key; then try the same triad with D in the bass. The surrounding notes decide how the moment functions.

Build B flat major from memory. Raise only its fifth. Play the result broken, then together, and name each four-semitone jump. If you can find both jumps without the note list, you can rebuild the chord from any root.