II-V-I Explorer
Click any note on the Circle of Fifths to hear the most important progression in jazz.
The II-V-I (two-five-one) is the most important chord progression in jazz harmony. It appears in virtually every jazz standard. The Roman numerals refer to chords built on the second, fifth, and first degrees of a major scale.
In C major: Dm7 - G7 - Cmaj7.
The II chord creates departure, the V builds tension, and the I resolves.
Jazz musicians practice this in all 12 keys because songs frequently modulate.
The Circle of Fifths arranges all 12 keys so each neighbor is a perfect fifth apart. Keys close on the circle share many notes, making modulations between them sound smooth.
For II-V-I: given any tonic (I), the V is one step clockwise and the II is one step counter-clockwise. The circle also reveals key signatures — clockwise adds sharps, counter-clockwise adds flats.
Voice leading moves each note to the nearest note in the
next chord. In Dm7 - G7 - Cmaj7, every voice moves by just
one step — D to C, F to E, A to G, C to B. This smooth motion is
why the II-V-I sounds so satisfying.
The voicing selector lets you hear how inversions affect the sound. Root position gives the textbook sound; inversions rearrange notes for different sonic qualities and smoother voice-leading.