One progression, two keys: I V vi IV
I-V-vi-IV in C is C-G-Am-F. In G it is G-D-Em-C. The same layout, different letters. Not every song walks that way.
Adrian3 minupdated
In C the writing is C-G-Am-F. In G the same four places are G-D-Em-C. Eight names look like two songs. It is one order: I-V-vi-IV.
C, then G
| scale degree | in C | in G |
|---|---|---|
| I | C | G |
| V | G | D |
| vi | Am | Em |
| IV | F | C |
Open Progression strum: I-V-vi-IV in C. Walk the loop. Then in the tool switch the key to G. The letters will change. Counting I-V-vi-IV will stay.
This layout shows up in pop. The example in the tool does not prove how popular it is, and it does not mean every four-chord song walks that way. A different start, or a different chord length, gives a different course.
The carol has these chords, but another route
W żłobie leży in C uses C, G, Am and F. The verse goes C, G, then Am with F, then G with C. That is not a clean I-V-vi-IV loop. The tool isolates the layout. The card shows how those four roles mix with 3/4 time and other changes.
Play I-V-vi-IV in C, then in G
In Progression strum open the loop in C. Then switch the key to G. The counting of scale degrees stays.
Measure: C-G-Am-F and G-D-Em-C are the same layout.