Inversions, Slash Chords and Voicings

Use a bass-first decision

Identify the chord tones before naming the inversion. If the bass is the root, the chord is in root position. If the bass is the third, fifth or seventh, it is respectively first, second or third inversion. Only after that decision should spacing, register, doubling and omissions be described as voicing.

For C major, C–E–G is root position, E–G–C is first inversion and G–C–E is second inversion. The upper voices may be rearranged freely without changing that label as long as the bass remains C, E or G.

Chord-tone slash basses

C/E instructs that E be the lowest note of a C-major harmony, so it is first inversion. C/G places the fifth in the bass and is second inversion. The slash is useful because it communicates bass identity without prescribing the exact octave or order of every upper note.

A symbol such as Cmaj7/B names third inversion because B belongs to Cmaj7 as its seventh. The chord explorer can rotate the complete note set, while the finder can test whether a selected bass belongs to the exact chord identity.

• C/E — E bass — first inversion
• C/G — G bass — second inversion
• Cmaj7/B — B bass — third inversion

Non-chord bass, pedal tones and voice leading

D/C contains a D-major triad above C. Because C is not D, F♯ or A, the sonority is not an inversion of D major. It may function as a chord over a pedal bass, a voice-leading event or a larger harmony whose name depends on context. The slash notation states the observable bass without pretending to settle that analysis.

A sustained pedal can remain while several upper chords change. Smooth bass motion can also motivate C–G/B–Am, where the middle chord uses B in the bass to connect C down to A by step. These are structural examples, not excerpts from or claims about named songs.

Same inversion, different voicing

C3–E3–G3, C3–G3–E4 and C2–G3–C4–E4 all retain C in the bass and are therefore root position. They differ in spacing and, in the last example, root doubling. “Close” usually keeps adjacent chord tones within one octave; “open” or “spread” moves one or more tones farther apart.

Register changes colour and playability without automatically changing chord identity. Omitting a structurally weak fifth may preserve a seventh chord’s defining third and seventh, but the omitted tone should be disclosed rather than silently presented as the complete formula.

Same pitch classes, different bass

The pitch-class set {C, E, G} supports all three C-major inversions. A reverse finder that ignores bass can identify the exact set but cannot name the inversion. Once the user designates E as lowest, first inversion becomes a justified label.

This separation prevents a common interface error: reporting one root-position name merely because the selected keys match a chord. Exact pitch set, harmonic root and actual bass are related but separate fields.