Question: what chords are in 12 bar blues?
Answer: The blues can be played in any key. In whatever key you are in, 12-bar blues uses the same basic sequence of I, IV, and V chords. It is most easily thought of as three 4-bar sections – the first 4, the middle 4, and the last 4 bars. The first 4 bars just use the I chord - I, I, I, I.