Five flats. Lovely on piano, awkward on guitar, so guitarists capo 1 and play in C.
| Chord | Number | Roman |
|---|---|---|
| D♭ | 1 | I |
| E♭m | 2m | ii |
| Fm | 3m | iii |
| G♭ | 4 | IV |
| A♭ | 5 | V |
| B♭m | 6m | vi |
| Cdim | 7° | vii° |
The 1, 4 and 5 (D♭, G♭, A♭) are the backbone. Add the 6m (B♭m) and you can play most of what's on the radio. The 7° (Cdim) mostly shows up as a passing chord, so don't lose sleep over it.
Those numbers are the Nashville number system. Learn the progression as numbers once and it works in every key.
Capo 1, play C shapes; capo 4, play A shapes; capo 6, play G shapes.
The capo chart has every key, and the transpose chart moves a song somewhere else entirely.
Songs that leave D♭ usually go to its 4 or 5: key of F♯ or key of A♭. Or see every key.
Chartless listens to whatever is playing and shows the key, the chords and the numbers live, so you can check a recording against this page while it plays. How to find the key by ear if you'd rather do it yourself.