Lessons · Intermediate
Bass Lines Over Chord Progressions: I-IV-V to Blues
Turn any chord chart into a bass line with roots, fifths, passing tones, pedal points and inversions, progression by progression.
A chord chart tells the guitarist and the pianist what to play, but for the bassist it is only the starting point. You choose which note of each chord goes to the bottom, how long it lasts and how you get to the next chord. This lesson walks through the most common progressions and gives you a method that works on all of them: anchor, connect, vary.
- Anchor: play the root on beat 1 of every new chord.
- Connect: use fifths, chord tones and passing tones to lead into the next root.
- Vary: once the line works, try pedal points, inversions and rhythmic changes.
All tab examples are for a 4-string bass tuned E1 A1 D2 G2.
I-IV-V: roots and fifths
The I-IV-V progression is the base of rock and roll, country, folk and blues. In A it is A, D and E. A root-fifth-octave pattern makes it sound full right away:
- A: A1, E2, A2, E2 (E string fret 5 shape).
- D: D2, A2, D3, A2 (the same shape one string higher).
- E: E1, B1, E2, B1 (the same shape using the open E string).
Hear the progression in G with a generated root-fifth line, then play along:
I-V-vi-IV: eighth notes and passing tones
The I-V-vi-IV progression drives a huge amount of pop music. In C it is C, G, Am, F. Driving eighth notes on the root are the classic approach, with a fifth for movement:
Now replace some notes with passing tones: scale notes on weak beats that walk from one root to the next. The line below stays in C major and moves mostly by step:
- C to G: C, C, B, A, then G. The line steps down through the scale.
- G to Am: G, G, A, B, then A. Up and back, landing on the new root.
- Am to F: G on beat 4 steps down into F.
- F to C: A, B leads up into C. B is the leading tone of C major, which makes the return very strong.
Rule of thumb: passing tones belong on beats 2 and 4 (or on off-beat eighths). The strong beats keep the chord tones.
ii-V-I: the jazz progression
In C the ii-V-I is Dm7, G7, Cmaj7. Jazz bassists usually walk over it: one quarter note per beat, root on beat 1, chord tones or scale notes on beats 2 and 3, and an approach note on beat 4.
The ii-V movement is a root falling a fifth (D to G, G to C). On bass that motion is easy to see: the next root is either on the same fret one string higher (a fourth up, A string fret 5 to D string fret 5) or one string lower and two frets lower (a fifth down, A string fret 5 to E string fret 3). Use the bass arpeggios lesson to learn the m7, 7 and maj7 shapes, and the walking bass lesson for complete walking lines.
Minor progressions
Minor keys use the same tools, with different notes for passing tones. Three common progressions in A minor:
| Progression | Chords in A minor | Bass approach |
|---|---|---|
| i-VI-VII-i | Am F G Am | Root-fifth, step up from F to G to A |
| i-iv-v-i | Am Dm Em Am | Roots on beat 1, natural minor passing tones |
| i-VII-VI-V | Am G F E | Descending roots: A G F E, very strong as a line |
i-VI-VII-i in A minor with root-fifth bass
Bass line: root, fifth, octave and approach note
When the V chord is major (E or E7 in A minor), its third is G#, not G. Avoid G natural as a passing tone over that chord, and use G# as a leading tone back to A instead. This is the harmonic minor sound.
Pedal points
A pedal point is a bass note that stays the same while the chords above it change. It builds tension and makes the band sound bigger. Common pedals:
- Tonic pedal: A under Am, F/A and G/A, then resolving to Am. Calm but intense.
- Dominant pedal: E under several chords before returning to A minor. Strong build-up into the next section.
Keep the rhythm simple during a pedal. The interest comes from the chords moving above you, not from the bass.
Inversions and slash chords
A slash chord such as C/E means "C chord with E in the bass". The letter after the slash is the bassist's note. Slash chords let you build smooth lines that move by step instead of jumping between roots.
| Symbol | Bass note | What it is | Typical use |
|---|---|---|---|
| C/E | E | First inversion (third in bass) | Stepwise line between D and F |
| C/G | G | Second inversion (fifth in bass) | Before G at a cadence |
| G/B | B | First inversion | Step down from C to A |
| Am/G | G | Third inversion of Am7 (seventh in bass) | Descending line A G F |
| F/G | G | Non-chord tone in the bass | Soft, suspended V chord |
The classic descending line: C, G/B, Am, Am/G, F, C/E, Dm7, G7. The bass walks down the C major scale while the chords change on top.
As written in a bass part, one octave above the sounding pitch:
The 12-bar blues
The 12-bar blues in A uses three dominant chords: A7, D7 and E7.
| Bars 1-4 | Bars 5-8 | Bars 9-12 |
|---|---|---|
| A7 A7 A7 A7 | D7 D7 A7 A7 | E7 D7 A7 E7 |
The most famous blues bass figure is the boogie line: root, third, fifth, sixth, flat seventh, sixth, fifth, third in eighth notes. One bar for each chord:
Play the A7 bar for bars 1-4, 7-8 and 11, the D7 bar for bars 5-6 and 10, and the E7 bar for bars 9 and 12. Then hear the full form with a simple root-fifth line:
12-bar blues in A with root-fifth bass
Bass line: root, fifth, octave and approach note
Practice
- Root lock: play every progression in this lesson with roots only, in quarter notes, at 80 BPM.
- Root-fifth: add fifths, then octaves, keeping beat 1 on the root.
- Passing tones: for each chord change, add one scale passing tone on beat 4.
- Slash line: play the descending C to G7 line, then write a rising version (C, C/E, F, G).
- Blues chorus: play three full choruses of the 12-bar blues with the boogie line without stopping.
Related lessons: Chord progressions, Diatonic harmony, Cadences, Bass basics, Bass arpeggios, Bass scales and modes, Walking bass, Bass groove and rhythm.
Tools: Progression player, Key finder, Transposer, Metronome.
Exercises: Root and fifth, Approach notes, Walking ii-V-I, Walking blues, Eighth-note grooves, Bass arpeggios.
Follow the 8-week intermediate bass path for a complete plan.