Key
Chords in Eb major
Eb major is built from the notes Eb, F, G, Ab, Bb, C and D. Its scale carries 3 flats. Harmonising that scale in thirds gives seven chords — 3 majors, 3 minors and 1 diminished — starting on Eb as the I. The chord on the fifth degree is Bb, a major V, so Eb major has the leading tone that makes a Bb-to-Eb cadence sound final.
Beyond those seven, Eb major commonly borrows Ebm (i), Fdim (iiø), Gb (bIII), Abm (iv) and Bbm (v) from the parallel minor — the mixture chords that give a progression somewhere unexpected to go.
The seven chords
Extended to four notes each, the same seven degrees give Ebmaj7, Fm7, Gm7, Abmaj7, Bb7, Cm7, Dm7b5.
Borrowed chords
Capo 3 and play C major shapes to sound Eb major.
All eight capo positions for Eb major →