Root, third and seventh: the guide tones fix the quality, so the fifth is dropped. That is what leaves a string free, so pick a tension to put on top.
Gm7 is G, Bb, D and F — Gm with the flat seventh added.
It sounds smooth and unhurried. The workhorse of the family, and the chord soul, funk and jazz comp on more than any other.
Pre-dominant — the ii of a major key, and a tonic in its own right.

| G | Bb | D | F |
|---|---|---|---|
| 1 | ♭3 | 5 | ♭7 |
Also written Gmin7, G-7 or G minor 7. The same chord either way; which spelling you meet depends on who wrote the chart.
Root, third and seventh. The third and seventh, the guide tones, are what make the chord major, minor or dominant, so the fifth can go: it says nothing the symbol needs.
Three notes means a spare string, which is the real point. Put a tension on it.
Gm7 has 7 of them, on the bottom three strings, the low-middle three, strings 6-4-3 and strings 5-3-2, from open position up to the 15th — all in one inversion, so the bass note never moves. The one to learn first is the G shape at the nut, which is the easiest grip here.
Play Gm7 as a shell — root, third and seventh — and the spare string takes the 9 (A), the 11 (C) or the 13 (E).
All 6 common shapes as fret numbers, lowest string first. Hover or tap one to see it drawn.
How you get to it. The turn that lands on Gm7 is Am7♭5 to D7♭9: the ii and the V of G minor, which is where a minor tonic is usually arrived at rather than simply begun on.
In which keys. Every note of Gm7 belongs to C minor (the v), D minor (the iv), Eb major (the iii), F major (the ii), G minor (the i) and Bb major (the vi).
Every note of Gm7 is in G minor pentatonic, G blues, G dorian, G natural minor and G phrygian.
Change one note of Gm7 and you have Gm (drop the flat seventh), Gm6 (the flat seventh becomes the sixth), Gm7b5 (the fifth becomes the flat fifth), Gm9 (add the ninth), GmMaj7 (the flat seventh becomes the major seventh) or Gmadd9 (the flat seventh becomes the ninth).
Gm7 is a minor chord — root, minor third, fifth. Minor chords on every root.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.