Chord Inversions

A chord keeps its name no matter which of its notes sits on the bottom. Play C, E, G and you have a C major chord. Now take that low C and move it up an octave so the notes read E, G, C. Same three notes, same chord, but a different note is now lowest. That rearranging is called an inversion.

Think of three people standing in a line who swap places. It is still the same three people; only their order changed. A chord works the same way: shuffle which note is on the bottom and it is still the same chord, just inverted.

Play C-E-G, then play E-G-C higher up. Both are C major, but the second one sits differently because E is now the lowest note.

The bass note carries more harmonic weight than any other voice. The lowest sounding pitch sets the foundation everything else is heard against, so changing it alters how stable or mobile a chord feels even when the notes above are untouched.

This split between a chord's identity and its bass runs through all of harmony. The root names the chord and never changes, while the bass is whatever note is lowest at the moment and can be any chord tone. When that lowest note is a chord tone other than the root, the chord is inverted. That split lets an analyst call a passage the tonic chord even as its bass walks up and down.

The first kind of inversion puts the middle note of the triad, the third, on the bottom. Take C major, C, E, G, and move the C up an octave. Now E is lowest and you have E, G, C. That is C major in first inversion.

It is still a C major chord, but it sounds a little lighter and less planted than when C was on the bottom. Composers use first inversion constantly to keep the bass line moving smoothly instead of leaping around.

Play C-E-G, then lift the C up an octave to make E-G-C. Same chord, but the second one feels a touch lighter on its feet.

First-inversion triads sound lighter and more mobile than root-position ones, and that quality comes from the intervals above the bass. With the third in the bass, the chord presents a sixth and a third over the lowest note instead of the fifth and third of root position, a spacing that sounds less grounded and readier to move on. Root position still sounds more final.

This is what made first inversion a mainstay of tonal writing. It lets a composer harmonize a moving bass line smoothly, supplying a chord under each passing bass note without forcing the bass to leap to every root, and it softens a run of chords that would sound heavy in root position. Bass lines can then move by step under full harmony.

The second kind of inversion puts the top note of the triad, the fifth, on the bottom. Start from C major once more, but move both C and E up so G is lowest: G, C, E. That is C major in second inversion.

This one sounds the least settled of the three. With the fifth in the bass, the chord feels like it is balancing on a point and wants to tip toward another chord. Because of that, classical composers use second inversion more carefully than the other arrangements, in a few particular spots.

Listen to G-C-E next to plain C-E-G. The second-inversion version sounds oddly suspended, as if it is waiting to resolve.

The second-inversion triad is singled out because of the fourth it forms above the bass. A perfect fourth between the bass and an upper voice was long treated as a dissonance requiring resolution, so a chord with its fifth in the bass contains a note that leans toward resolution.

Each convention manages that unstable fourth. The cadential 6/4 delays the dominant while its upper voices lean downward into it; the passing 6/4 harmonizes a bass moving stepwise between two positions of one chord; the pedal 6/4 decorates a held bass.

Seventh chords have four notes, so they have one more possible bottom note than triads do. Along with root position and the first two inversions, a seventh chord can put its fourth note, the seventh, in the bass. That gives a third inversion.

So a seventh chord comes in four arrangements: root in the bass, third in the bass, fifth in the bass, or seventh in the bass. Each keeps all four notes and the same chord name; only the lowest note changes, one more option than a triad has.

A G seventh chord, G-B-D-F, has four notes, so try putting each one on the bottom in turn. Every version is still a G seventh chord.

The extra note gives seventh chords a flexibility triads lack, since any of four tones can support the harmony in the bass. The dominant seventh shows this most clearly: its inversions place the leading tone, the chord's fifth, or the chordal seventh in the bass, each setting up a specific stepwise resolution into the tonic chord.

Third inversion is the distinctive one. With the seventh in the bass, the chord's most active, resolution-seeking note becomes its foundation, and that note conventionally falls by step into the next chord. So the inversion shapes the voice leading, and analysts read a seventh chord's bass note as closely as its root.

When a chord is inverted, its notes look jumbled, so how do you tell which chord it is? The trick is to restack the notes into a neat pile of skips, root, third, fifth, and see what lands on the bottom. Given E, G, C, rearrange them as C, E, G and you see the root is C: it is a C chord.

That restacking is the key skill. Once you can rebuild any inverted chord into its tidy stacked-thirds shape, you can always name it, no matter which note happened to be in the bass.

Take the notes G, C, E and shuffle them until they stack in skips. They become C, E, G, so the chord is C major, just in an inversion.

Finding the root by restacking works because inversion never changes which notes are present, only their vertical order. A chord is defined by its spelled note names, whatever octave they sit in, so stacking those letters back into thirds always recovers the same root, and an analyst can label a chord identically in any of its positions. The same restacking works whether the third, the fifth, or the seventh is in the bass.

Choosing inversions is one of the main tools of voice leading. By selecting which tone falls in the bass, a composer controls the shape of the lowest line, avoids clumsy leaps, and paces where stability lands across a phrase. Progressions and figured bass, in later classes, assume you already control the bass this way.