Blues chords are mostly dominant seventh chords built on the I, IV, and V of a key. In the key of C, that means C7, F7, and G7. Arrange them over 12 bars and you have the 12-bar blues, the backbone of the genre.
Every blues great started with a few shapes. B.B. King, born in 1925 on a Mississippi cotton plantation, learned his first chords from his uncle, according to the National Endowment for the Arts.
This lesson covers the 12-bar blues and nine chord shapes to play it with. You’ll learn each chord in C, then its seventh version.
the I, IV, and V of your key, usually played as seventh chords
What Is the 12-Bar Blues Progression?
The 12-bar blues is a progression of three four-bar phrases. In its basic form, bars 1 to 4 stay on I. Bars 5 to 8 play IV, IV, I, I, and bars 9 to 12 play V, IV, I, I.
Two variations are especially common. Bar 2 often moves to IV, and the last bar often switches to V, a turnaround back to the top. Here’s a popular version that uses both:
- Bars 1 to 4: I, IV, I, I
- Bars 5 to 8: IV, IV, I, I
- Bars 9 to 12: V, IV, I, V
After bar 12, the pattern repeats for as long as the song lasts.
Why Do Seventh Chords Sound Bluesy?
You can play the blues with plain major chords, but the bluesy sound comes from dominant seventh chords. A dominant seventh is a major triad plus a minor seventh above the root. C7, for example, is C–E–G plus B♭.
In a standard 12-bar blues, every chord is a dominant seventh, not just the V. That unresolved tension on the I and IV chords is the blues flavor.
How Do You Play Blues Chords in C Major?
Let’s build the progression in the key of C major. Play each major shape first, then its seventh version, and compare the two.
Open C Major Chord (I Chord)
Start with the open C major chord, the I chord in this key.
- Place your 1st finger on the 2nd string, 1st fret.
- Place your 2nd finger on the 4th string, 2nd fret.
- Place your 3rd finger on the 5th string, 3rd fret.
- Place your 4th finger on the 1st string, 3rd fret.
- Play the 3rd string open, and mute the 6th string.
C7 Chord: Blues It Up
To blues it up, start the progression with a C7 chord instead. Your fingers shift, and the 2nd string is now muted.
- Place your 1st finger on the 4th string, 2nd fret.
- Place your 2nd finger on the 5th string, 3rd fret.
- Place your 3rd finger on the 3rd string, 3rd fret.
- Place your 4th finger on the 1st string, 3rd fret.
- Mute the 2nd and 6th strings.
Hear the difference? Your 3rd finger now adds B♭, the minor seventh above C, and the chord turns bluesy.
F Major Barre Chord (IV Chord)
Next comes the IV chord, a standard F major barre chord. The diagram marks your 1st finger on the 1st string only, but it presses all six strings.
- Lay your 1st finger flat across all six strings at the 1st fret.
- Place your 2nd finger on the 3rd string, 2nd fret.
- Place your 3rd finger on the 5th string, 3rd fret.
- Place your 4th finger on the 4th string, 3rd fret.
F7 Barre Chord
Now try the F7 barre chord and note the difference. It’s the same shape with your 4th finger lifted.
- Lay your 1st finger flat across all six strings at the 1st fret.
- Place your 2nd finger on the 3rd string, 2nd fret.
- Place your 3rd finger on the 5th string, 3rd fret.
Just one note changes. With your 4th finger lifted, the barre plays E♭ on the 4th string, the minor seventh above F.
Open G Major Chord (V Chord)
The V chord in this progression is the open G major chord.
- Place your 1st finger on the 5th string, 2nd fret.
- Place your 2nd finger on the 6th string, 3rd fret.
- Place your 3rd finger on the 2nd string, 3rd fret.
- Play the 1st, 3rd, and 4th strings open.
G7 Chord
For comparison, try a G7 chord instead. Your 1st finger adds F on the 1st string, the minor seventh above G.
- Place your 1st finger on the 1st string, 1st fret.
- Place your 2nd finger on the 5th string, 2nd fret.
- Place your 3rd finger on the 6th string, 3rd fret.
- Place your 4th finger on the 2nd string, 3rd fret.
- Play the 3rd and 4th strings open.
How Do You Put the 12-Bar Blues Together?
You now know every chord for a 12-bar blues in C major. Play the progression with C, F, and G, then with C7, F7, and G7, and hear the mood change.
Loop the C7 to F7 switch slowly, four beats each, until the barre sounds clean. Then play all 12 bars and raise the tempo a little at a time.
Which Other Seventh Chords Should You Learn Next?
Once the progression feels comfortable, vary your rhythm. Move from quarter notes to straight eighths, a shuffle, or sixteenth-note patterns.
Study the blues greats for ideas, too. The Rock & Roll Hall of Fame notes that Eric Clapton, Jimi Hendrix, and Stevie Ray Vaughan cite Buddy Guy as an influence.
[Buddy Guy is] without a doubt the best guitar player alive.
Eric Clapton in 1986, as quoted by the Rock & Roll Hall of Fame
To play the blues in other keys, you’ll need more seventh chords. These three open up the key of A, where A7 is the I chord, D7 the IV, and E7 the V.
D7 Chord
D7 uses only the top four strings, so avoid strumming the 5th and 6th.
- Place your 1st finger on the 2nd string, 1st fret.
- Place your 2nd finger on the 3rd string, 2nd fret.
- Place your 3rd finger on the 1st string, 2nd fret.
- Play the 4th string open, and mute the 5th and 6th strings.
A7 Chord
This A7 uses no open strings, so you can slide the shape along the neck for other seventh chords.
- Place your 1st finger on the 5th string, 4th fret.
- Place your 2nd finger on the 6th string, 5th fret.
- Place your 3rd finger on the 4th string, 5th fret.
- Place your 4th finger on the 2nd string, 5th fret.
- Mute the 1st and 3rd strings.
E7 Chord
E7 is the V chord in A and the I chord in the key of E.
- Place your 1st finger on the 5th string, 2nd fret.
- Place your 2nd finger on the 2nd string, 3rd fret.
- Place your 3rd finger on the 3rd string, 4th fret.
- Place your 4th finger on the 1st string, 4th fret.
- Play the 4th and 6th strings open.
How Do You Find the I, IV, and V Chords in Any Key?
The chart below lists the chords in 12 major keys. For a basic blues, read the I, IV, and V columns and play each chord as a seventh.
In G, for example, the row gives you G, C, and D, so you play G7, C7, and D7.
Which Scales Work With the Blues?
When you’re ready to solo, this chart shows three scale families: minor pentatonic, the blues scale, and Mixolydian. The diamonds mark the root note.
Start with the first minor pentatonic shape, then add the extra note of the blues scale.
Now Play the Blues
Keep learning chord shapes and strumming patterns to build your blues rhythm. Listen to the players you love, and happy practicing!
Sources
- "Blues Harmony," Bryn Hughes and Megan Lavengood, Open Music Theory, Version 2. Available at: https://viva.pressbooks.pub/openmusictheory/chapter/blues-harmony/. Accessed 28 Sept. 2026.
- "Seventh Chords," Chelsey Hamm, Open Music Theory, Version 2. Available at: https://viva.pressbooks.pub/openmusictheory/chapter/seventh-chords/. Accessed 28 Sept. 2026.
- "Riley “B.B.” King," National Heritage Fellowships, National Endowment for the Arts. Available at: https://www.arts.gov/honors/heritage/riley-bb-king. Accessed 28 Sept. 2026.
- "B.B. King," Rock & Roll Hall of Fame. Available at: https://rockhall.com/inductees/bb-king/. Accessed 28 Sept. 2026.
- "Buddy Guy," Rock & Roll Hall of Fame. Available at: https://rockhall.com/inductees/buddy-guy/. Accessed 28 Sept. 2026.
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