12 Bar Blues – The Foundation of Blues & Rock

The 12 Bar Blues format is the foundation of most blues music.  But what many people don’t know is that the 12 Bar Blues format is also critical to rock and pop music as well.  Learning the 12 Bar Blues format will open up all kinds of musical options for you.  And it will teach you arguably the most important chord progression for guitar players.

12 Bar Blues Keith Richards Quote

This blog will explain the basics of the 12 Bar Blues, including:

  • Chord Structure
  • Chords for Each Key
  • Shortcut for Finding Chords
  • Chord Progressions
  • Example of a 12 Bar Blues in E

12 Bar Blues Chord Structure

The 12 Bar Blues has a very distinctive structure that can be applied to any key.  It consists of 3 chords that are arranged in various patterns over 12 bars of music. Knowing which chords to play and when is the essence of becoming a fluent blues and rock guitarist.

Let’s start with learning which chords are played in a 12 Bar Blues song. The chords are always called the (I) chord, (IV) chord and (V) chord.  For clarity, these notations are using roman numerals and when spoken they are referred to as “the one chord”, “the four chord” and “the five chord”. If you’re asking yourself what the (I), (IV) and (V) chords mean or why roman numerals are used, it’s a very good question. And I’m happy to explain!

To get just a bit technical into some music theory, the roman numerals denote scale degrees.  And when representing a chord, they denote the root note on which the chord is built. The concept of the (I) chord, (IV) chord and (V) chord is based on the major scales.

For any given key, if a chord is built from the first note of the major scale, it is called the (I) chord.  Similarly, chords built from the fourth note of the major scale is called the (IV) chord.  And yes, you guessed it, chords built from the fifth note of the major scale is called the (V) chord.

Let’s use an example to make this concept more clear and easy to understand.  If we want to play a 12 Bar Blues in the key of A, we first have to start with knowing the notes of the A Major Scale.

12 Bar Blues A Major Scale

Aligning each note of the scale with ascending roman numerals, you will see that the (I), (IV) and (V) chords are A, D and E.

By the way, if you need a refresher on how to identify the notes of a major scale, check out my blog on scales.

12 Bar Blues Chords for Each Key

Now you might be thinking, “That’s great for the key of A, but what about the rest of the keys?”

The table shown below defines the (I), (IV) and (V) chords for all keys.  Notice that the note name of the key always matches the note name of the (I) chord.

12 Bar Blues Chord Progression

Also know that if you’re playing other forms of chords, such as minor chords or dominant 7thchords, the notes in the table above still hold true. For example, when using 7thchords the (I), (IV) and (V) chords in the key of A would be A7, D7 and E7, respectively.

12 Bar Blues Shortcut for Finding Chords

If it takes you a while to memorize the table above, don’t fret (guitar pun!).  There’s a fairly easy way to quickly find the root notes of the (I), (IV) and (V) chords within a key when the root note is on the sixth string.  Let’s first review the shape of a Major Scale on the guitar fretboard.

Major Scale Chord Chart

Notice that I’ve numbered the first five notes of the Major Scale pattern. Starting with the sixth string, whichever note you’re playing is the root note.  And it is also the name of the (I) chord and the key.  To find the (IV) chord, just move your fretting finger to the same fret but now on the fifth string instead of the sixth string.  And to find the (V) chord, just slide your fretting hand up two frets along the fifth string on the fretboard.  This handy trick works for any key!

Below is an example using the key of A, with the (IV) and (V) chords being D and E, respectively.

12 Bar Blues Key of A Fretboard

Sometimes, you’ll find yourself wanting to play a 12 Bar Blues with the root note of the (I) chord on the fifth string instead of the sixth string. Fortunately, there’s another simple pattern to help you always find the (IV) and (V) chords.  From wherever you start on the fifth string root note, the (V) chord is always the same fret just moved to the sixth string.  And the (IV) chord is just down two frets on the fretboard (as it always is).

Below is an example using the key of D, with the (IV) and (V) chords being G and A, respectively.

12 Bar Blues Key of D Fretboard

12 Bar Blues Chord Progressions

Now we’re ready to move on to knowing when to play each chord throughout the 12 bars of the song.  There are three common 12 Bar Blues formats.  And each of them only differs in one of the 12 bars.  The three types are basic, repeating and quick-change.

12 Bar Blues – Basic Format

12 Bar Blues Chord Progression Basic

This basic format is used when you’re just playing through a single round of the 12 Bar Blues.  It is also very common for any song that extends into multiple instances of the 12 bars form to end on this basic structure.

12 Bar Blues – Repeating Format

12 Bar Blues Chord Progression Repeating

Notice the change in the very last bar.  When a 12 Bar Blues repeats several times throughout a song, it is typical for the 12thbar to end on a (V) chord.  This is known as a turnaround and it really sets up the next instance of 12 bars so as not to repeat the (I) chord too many times in a row.

12 Bar Blues – Quick Change

12 Bar Blues Chord Progression Quick Change

The only difference in the Quick Change Blues format is in the second bar. The normal (I) chord is replaced with a (IV) chord.  This gives the sound just a bit more variety rather than repeat the (I) chord for four straight bars.

Are You Ready for the Real Deal?

If so, check out the simplest of 12 Bar Blues rhythms.  This is a basic 12 Bar Blues in the Key of E using two-note power chord shapes.  Even though it’s simple, it’s wildly popular in blues and rock music and is a favorite of musicians playing together at blues jams.  And while playing full 7thchords is going to sound fuller, especially when playing on your own, most guitarists use these smaller versions of chords when playing rhythm in a band or jam situation.

12 Bar Blues Key of E

If you’ve made it to the end of this blog, congratulations!

You are now equipped with some sound knowledge of the 12 Bar Blues and how it applies to blues and rock and roll music.  With regular practice of the 12 Bar Blues in different formats and in different keys, you’ll be able to play along with friends and your favorite blues and rock songs.  Good luck!

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