The most used loops (in C / A minor)
- I–V–vi–IV: C G Am F. The “universal” pop progression.
- vi–IV–I–V: Am F C G. The same progression rotated: more ambiguous center, more melancholic.
- I–vi–IV–V: C Am F G. The 1950s “doo-wop.”
- IV–V–iii–vi (“royal road,” 王道進行): Fmaj7 G7 Em7 Am. A pillar of J-pop and many K-pop ballads.
- i–VI–III–VII: Am F C G in a minor key: trap, emo rap, EDM.
- I–bVII–IV–I: C Bb F C, Mixolydian rock.
- ii–V–I pop: Dm7 G7sus4 G7 Cmaj7.
- I–iii–IV–iv: C Em F Fm, with the minor borrowing to close.
Rotation and tonal center
The same four triads change meaning depending on the starting point, the longest chord, the bass and the melody. If the topline ends on A, Am F C G sounds in A minor; if it ends on C over C, the center becomes C.
How to make a common progression fresh
- Inversions in the bass: C – G/B – Am – F (descending bass C B A F).
- Sus and add: Cadd9 – Gsus4 – Am7 – Fmaj7.
- Interchange: replace the last F with Fm.
- Harmonic rhythm: two chords per bar in the chorus, one every two bars in the verse.
- Pedal chord: everything over a C in the bass.
Real example
“Let It Be” by the Beatles in C opens with C G Am F; “Despacito” (Luis Fonsi ft. Daddy Yankee, 2017) uses the vi–IV–I–V rotation (Bm G D A, in D major).