Blues Guitar Chords Tutorial: The Twelve Bar Blues

This article expands on your knowledge of blues guitar chords by
explaining how to play the twelve bar blues, which is the basis
of many blues songs.

For this article, you should know how to play the following
basic guitar chords: C, F, G, and the following essential blues
guitar chords: C7, F7, G7. If you don't know how to play those
chords, read my article "Blues Guitar Chords Tutorial: 7
Essential Blues Guitar Chords".

Twelve Bar Blues Basics

Not every blues song is based on the twelve bar blues, but many
are, and it's the essential blues chord progression. "Twelve
bar" means that it's a chord progression consisting of twelve
bars, or measures. Each measure is four beats long. So a twelve
bar blues has twelve measures, each of which contains four beats.

The One-Four-Five Progression

The next thing we need to learn in order to play the blues is
that the twelve bar blues is what's called a "One-Four-Five"
progression (or 1-4-5, or I-IV-V). This means that in any key,
the blues progression uses three chords, which are known as the
One, 1, or I chord, the Four, 4, or IV chord, and the Five, 5,
or V chord. From now on, I'll use the roman numerals I, IV, and
V to denote the chords. So, what are the I, IV, and V chords? In
any key, the I chord is the major chord with the same name as
the key. So in the key of C, the C chord is the I. Now, if you
count up the scale, with C as I, you can find the IV and V
chords. I=C, II=D, III=E, IV=F, V=G. So in C, the I chord is C,
the IV is F, and the V is G. So those are the three chords you
need to play the blues in C.

Back to the Twelve Bar Blues

Now that we understand the meaning of the I, IV, and V chords,
we can learn the structure of the twelve bar blues progression.
Think of it as three sections, each having four bars. The first
section is four bars of the I chord. In C, this would be written
as follows:

C / / / C / / / C / / / C / / /

In that notation, each chord name (i.e., C) or slash mark (i.e.,
/) is a beat. You play the named chord once for every beat. The
slash marks just indicate that you stay on the same chord. We
give the chord name (i.e., C) again at the start of each measure.

The second four bar section has two bars of the IV chord
followed by two bars of the I chord. Again, in C:

F / / / F / / / C / / / C / / /

The final four bar section has a bar of the V chord, a bar of
the IV chord, a bar of the I chord, and a final bar of the V
chord. Again, in C:

G / / / F / / / C / / / G / / /

So, putting it all together, one version of the twelve bar blues
in C would look like this:

C / / / C / / / C / / / C / / /

F / / / F / / / C / / / C / / /

G / / / F / / / C / / / G / / /

Adding The Seventh Chord

To get the real blues sound, you'll want to add the 7th chord in
some places. This is different from the I, IV, V numbering
system; the Seventh in this case is part of the chord's letter
name (like C7, D7, or G7). In the blues, you almost always will
want to substitute a seventh chord for the V, and sometimes for
the I. Confusing? It just means that in C, where the V chord is
G, you will play G7 instead of G major.

For simplicity's sake, you can just use 7th chords throughout
the 12 bar progression:

C7 / / / C7 / / / C7 / / / C7 / / /

F7 / / / F7 / / / C7 / / / C7 / / /

G7 / / / F7 / / / C7 / / / G7 / / /

But for a more authentic sounding blues, we'll substitute the
7th chord for the V, and for the I and IV in certain places as
well. We'll also go to the IV chord in the second measure to add
variety (some players call this a 'quick IV' progression).

C / / / F / / / C / / / C7 / / /

F / / / F7 / / / C / / / C7 / / /

G7 / / / F / / / C / / / G7 / / /

Now that you know how to play the twelve bar blues in C, you
can use your knowledge of essential blues guitar chords and the
I, IV, V progression to play the blues in several keys. For more
information, look up my article "Blues Guitar Chords Tutorial: 7
Essential Blues Guitar Chords."