Have you ever wondered why all pop songs sound the same? Many pop songs are four chord songs. A four chord song is musically simple, and most of accompaniment is just four chords. Here’s more info on the basic music theory for understanding pop songs.
Roman numerals indicate the relationships between the chords in any key. The most common 4 chords are (I IV V vi). Below is a list of four chord songs ordered by chord progression. As a sidenote, music has no clear-cut rule that says pop songs can only use these 4 chords. Music is pretty flexible. The list below is more of a statistical analysis.
I recommend first learning the beginner ukulele chords Am, C, F, G. This is because in the key of C major, the I chord is C, the IV chord is F, the V chord is G, and the vi chord is Am. For example, the entire song Viva la Vida is F, G, C, Am (IV V I vi). You may have to transpose the songs to C major. For example, Pompeii transpose +5 is F, C, Am, G (IV I vi V). Here is more information on transposing songs and understanding song chords.
I IV vi V
I V vi IV
I vi IV V
I vi V IV
IV I V vi
IV I vi V
IV V I vi
IV V vi I
vi I IV V
vi I V IV
vi IV I V
vi IV V I
vi V I IV
vi V IV I