12-Bar Blues
The 12-bar blues is a specific 12-measure chord progression using three dominant 7th chords — I7, IV7, and V7. It is the most widely used chord structure in Western popular music, forming the backbone of blues, early rock and roll, jazz, and R&B. All 12-bar blues share the same harmonic skeleton: four bars on I, two on IV, two on I, then V–IV–I in the final four measures.
4 progressions — shown in G major
Transpose to your key →12-Bar Blues (Standard form)
Roman numerals
The standard 12-bar form, one chord per measure: 4 bars of I7, 2 bars of IV7, 2 bars of I7, then V7–IV7–I7–I7 to close. Every bar is one chord. This specific pattern is universal across all blues styles — from Delta to Chicago to Texas to jump blues. Tempo, style, and ornamentation vary; the form does not.
Quick-Change 12-Bar
Roman numerals
Bar 2 moves to IV7 (C7) instead of staying on I7, then returns to I7 in bar 3. The "quick change" creates more harmonic movement in the opening phrase. Used by Robert Johnson, Muddy Waters, and many traditional Delta blues players. The rest of the form is identical to the standard 12-bar.
Minor 12-Bar Blues
Roman numerals
All three blues chords become minor 7ths in the same 12-bar structure. The minor blues carries a darker, more somber quality. Common in jazz blues contexts — the final four bars often use a ii–V–i turnaround (Am7–D7–Gm7) instead of the standard V–IV–I, adding jazz harmonic sophistication to the minor form.
Jazz Blues Turnaround (ii7–V7–I7)
Roman numerals
In jazz blues, bars 9–10 replace the standard V7–IV7 with a ii7–V7 approach to the I7. In G: Am7–D7–G7. This more sophisticated resolution is standard in jazz blues contexts and many swing-era blues recordings. The ii7 softens the approach compared to the raw V7 of the standard blues form.
How 12-Bar Blues Works
Every chord in these progressions uses Roman numeral notation — uppercase (I, IV, V) for major chords, lowercase (ii, vi, i) for minor chords. The Roman numeral tells you which scale degree the chord is built on, making the progression key-independent.
To play 12-bar blues in a different key, apply the same degree relationships to the new key. Use our Chords in a Key tool to see all diatonic chords for any key, or the chord transposer to convert a chord chart to any key instantly.
Play These Progressions in Any Key
Each diatonic chord reference page shows you the exact chord names for every scale degree in that key — so you can apply any of these Roman numeral patterns directly. Click a key to see its full chord set:
Frequently Asked Questions
What is the 12-bar blues chord progression?
The 12-bar blues is a 12-measure chord pattern using I7, IV7, and V7. Standard form in G: G7 (bars 1–4) – C7 (bars 5–6) – G7 (bars 7–8) – D7 (bar 9) – C7 (bar 10) – G7 (bars 11–12). The pattern — 4 bars on I, 2 on IV, 2 on I, then V–IV–I–I to close — is universal across all 12-bar blues styles.
What key is the 12-bar blues usually in?
Blues is most commonly played in E, A, G, and Bb. E and A are popular on guitar due to open-string positions for string bending and vibrato. Bb is the most common key for horn-led blues bands. Jazz blues uses Bb, F, and Eb most often. The 12-bar form works identically in all 12 keys.
What is the quick-change variation of the blues?
In standard 12-bar blues, bars 1–4 stay on I7. The quick-change variation moves to IV7 in bar 2, then back to I7 in bar 3. This creates more harmonic movement in the opening phrase: I7–IV7–I7–I7 instead of I7–I7–I7–I7. Robert Johnson and many Delta blues musicians used the quick-change variation.
How does the 12-bar blues relate to rock and roll?
Early rock and roll was built almost entirely on the 12-bar blues. Chuck Berry, Little Richard, Elvis Presley, and Buddy Holly used the 12-bar form as the foundation. Rock eventually adapted it — retaining the I–IV–V movement while dropping the strict 12-bar structure and the dominant 7th chord on the I position.
Related Chord Progressions
Write chord charts for these 12-bar blues in Chordly — add lyrics, transpose instantly, and share with your band.
Drag and drop chords directly onto your lyrics, build guitar tabs, and practice hands-free with autoscroll Play Mode. All in your browser — no download needed.