Parallel motion
Parallel motion means: two or more voices move in the same direction and keep their distance. It is the special case of similar motion in which the interval does not change. Depending on the interval it sounds sweet, empty, powerful or forbidden.
- Meaning
- same direction, same distance
- Umbrella term
- similar motion
- Desirable
- thirds and sixths, six-three chords
The same distance, the same direction
When two voices move from one sonority to the next they have four possibilities: contrary motion, oblique motion, similar motion (same direction, changing distance) and parallel motion (same direction, same distance). One speaks of diatonic parallel motion when only the distance in steps stays the same, and of real parallel motion when the exact size of the interval stays the same too, for instance in a sequence of fifths that move by exactly the same number of semitones.
Parallel thirds
Two voices rise together and return at the end, the upper always a third above the lower. Looking closely the third alternates between major and minor (C–E major, D–F minor), but its distance in steps stays the same. That is parallel leading within a scale.
Parallel six-three chords
A chain of chords in first inversion, each a step higher: E–G–C, F–A–D, G–B–E, A–C–F. All the voices rise in step. In the music of the 15th century this kind of writing is called fauxbourdon.
What sounds good and what does not
Parallel thirds and sixths sound soft and fuse, but the voices stay recognisable as two. That is why they are allowed and popular in harmony teaching, for example in a duet. Parallel fifths and octaves, by contrast, let two voices fuse into one and count as mistakes in strict teaching, see Parallel fifths. If you want parallel intervals, you usually stick to thirds, sixths or whole chords.
A chain of six-three chords, as in the second line, is the classic exception. Here all the voices run in parallel, and yet it does not offend against the ban on fifths, because in a chord in first inversion only thirds, fourths and sixths arise between the voices, no fifths or octaves. More on inversion at Chord inversion.
Parallels in everyday guitar playing
On the guitar parallel motion is a basic skill: a barre chord can be slid as a whole up or down the fretboard, and all the notes move by the same distance. If you shift the same shape across the strings instead, the exception comes into play that the article on the shift describes: between the G and B strings there is only a major third instead of a fourth. Power chords do the same, described on the page Power chord. They consist of root and fifth and are deliberately led in parallel in rock music.
Common mistakes
- Equating parallel motion with similar motion: similar motion is the umbrella term. Parallel means the distance stays the same.
- Taking all parallels as forbidden: in strict teaching mainly fifths and octaves (also unisons) between independent voices are frowned upon.
- Writing long chains of thirds without variety: many textbooks recommend interrupting them.
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Related terms
Similar motionContrary motionOblique motionParallel fifthsParallel thirdsChord inversionPower chordIntervalTriad
Editor: Maik Krohm · reviewed on 3 October 2026
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