How to play Cm7 (C m7) on Bass

Cm7 is the C m7 chord. It is built from 4 notes — C, D#, G and A# — which sit at the root, minor third, perfect fifth and minor seventh above the root C. Written as a formula that is 1P – 3m – 5P – 7m. Those intervals, not the note names, are what give the chord its character: move all of them to a different root and you still hear a m7 chord.

Cm7 on bass is a movable shape with no open strings, fretted between fret 8 and fret 10, the shape spans 3 frets, 2 strings are muted and should not sound — damp them with the underside of a fretting finger. Since the shape uses no open strings it is fully movable: slide it one fret higher and you have the same chord a semitone up, which is the cheapest way to learn eleven more chords from one hand position.

The interval that defines this chord is the minor third between C and D#. Lowering the third by one semitone is the entire difference between C major and C minor, and it is the reason the chord reads as darker or sadder to most listeners. The added minor seventh stops the chord from sounding like a resting place — it leans forward and wants to resolve, which is exactly why it turns up at the end of a phrase rather than the start.

Cm7 belongs to 3 major keys, including Bb major, where it is the ii chord, Eb major, where it is the vi chord and Ab major, where it is the iii chord. That is the practical reason to learn it: a chord that is diatonic to several keys turns up constantly, and knowing which degree it occupies tells you what tends to come next. A ii chord in Bb major most often moves toward the tonic, so practising Cm7 in the context of Bb will teach you more than practising it in isolation.