In C major the seven diatonic chords are: C, Dm, Em, F, G, Am, Bdim. In Roman numerals: I ii iii IV V vi vii°. Everything below is built from that set.

I-V-vi-IV in C: C-G-Am-F

The pop workhorse. Piano fingering (right hand): C (1-3-5 on C-E-G), G (1-3-5 on G-B-D), Am (1-3-5 on A-C-E), F (1-3-5 on F-A-C). Guitar shapes: open C, open G, open Am, F barre or F/C easier voicing (x-3-3-2-1-0).

Let It Be is in C major with this progression. Sing along and you have located the shape in your ear.

ii-V-I in C: Dm-G-C (or Dm7-G7-Cmaj7)

The jazz cadence. Piano seventh voicings: Dm7 (D-F-A-C), G7 (G-B-D-F), Cmaj7 (C-E-G-B). Notice how the top note walks down by step: C to B (Dm7 to G7 shares the C-to-B move), then B to C on the final chord. That semitone motion is the ii-V-I sound.

I-IV-V-I in C: C-F-G-C

The simplest complete progression. Three chords, four bars, home. Every folk song, every hymn, every 12-bar blues shell reduces to this.

vi-IV-I-V in C: Am-F-C-G

Same four chords as I-V-vi-IV, rotated. Starts minor, resolves major. Zombie by the Cranberries lives in this shape (in E minor, but the pattern is identical).

Fingering ladder for adult beginners

1. Week 1: hold each chord (C, F, G) cleanly for four counts. Metronome at 60.
2. Week 2: change between C and F. Slow and clean beats fast and clumsy.
3. Week 3: full I-IV-V-I cycle. Sing the root of each chord.
4. Week 4: add vi (Am). Play I-V-vi-IV, sing along to Let It Be.

Hear it in every key

Open the chord progression generator, set the key to C, and play through each preset. Then move to G major and try the same shapes; you will find them faster than you expect.