Like triads, seventh chords can be inverted by moving the lowest note up an octave.
Root position is the same as a triad – the root is the lowest (bass) note.
First inversion is also the same – the third is the lowest note.
Let's invert the chord again.
Second inversion is also the same – the fifth is the lowest note.
Let's invert the chord again.
Now, the seventh is the lowest note of the chord.
This is called third inversion.
Let's invert the chord one more time.
Notice that the chord returns to root position.
Use this chart for reference to seventh chord inversion.