12 Bar Blues question

Hi All, I can’t find the answer to this but I thought there was a term for this. Is there a term for each of the sections of 4 bars in the 12 bar blues? ie first 4 bars are called, ‘phase 1’ or something like that? No problem if not, just thought I’d heard it somewhere and now can’t find it.



I do not think there is, but:

The first 4 bars are usually the “I chord section” or where the “quick change” is.

The middle 4 bars are the “IV chord” section as bars 5 and 6, especially the bar 5 is almost always the IV chord, even in jazz.

The last 4 bars are where the V → IV transition, or where the “turnaround” is.

Not what you are looking for but this is the closest I can get.


Hi @ukbuk , no such luck there. The 12 bar structure is denoted by the chords used, represented by Roman numerals rather than chord. Usually I , IV and V for 1,4 and 5.

The most basic form is

| I. | I. | I. | I. |
| IV | IV | I | I. |
| V. | IV. | I. | I. |

If it is a blues in A, I= the A chord, IV is the D chord and V is the V chord.

Then two important varying parts are bar 2, which would become the IV chord e.d. D. This is called a quick change. The last two bars e.g. 11 and 12 also can vary, they could contain a turnaround, which is used to denote the end of the 12 bar progression, by going from the I chord to the V chord, e.g from A to E .

Apart from a few other more special forms, that is about it.

Usually the lyrics in bars 1 to 4 are repeated in 5 to 8, the last 4 bars differ as a rule.

That is about it. Hope this helps


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Mostly, if you want to discuss or single out a smaller part of the 12-bars, it would be by naming a bar or bars.

Shall we do a quick change in bar 2?

Can we add a maj7 chord in bar 9?


I’ve heard bars 1–4 referred to line 1, bars 5–8 as line 2, etc. But, agree with @Richard_close2u that most commonly specific bars are referred to.

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Great thanks for the help all. Was aware of the general form from Justin’s videos but just wanted to make sure I wasn’t missing anything.