Triad Inversions

After this lesson, you will be able to construct and name root position, first inversion, and second inversion from the actual bass. You will also connect nearby C, F, and G shapes instead of returning to root position after every chord.

The bass determines inversion

A triad is in root position when its root is lowest, first inversion when its third is lowest, and second inversion when its fifth is lowest. For C major, bass notes C, E, and G define those three positions. In common Roman-numeral figures, I is root position, I6 is first inversion, and I6/4 is second inversion. The figures describe intervals above the bass.

Do not infer inversion from the order of right-hand notes alone. If the left hand holds E3 while the right plays G4–C5–E5, the complete texture is still C/E in first inversion, even though E is also on top. Always find the lowest sounding pitch across both hands.

Inversion is not voicing

E3–G3–C4 and E3–C4–G4 are different voicings of the same first-inversion C chord. E remains the bass and the pitch content remains C–E–G. Changing spacing, doubling a member, or distributing notes between hands can change voicing without changing inversion.

By contrast, lowering the bass from E3 to C3 immediately changes the label to root position, even if the right hand remains fixed. A slash symbol such as C/E makes bass explicit. A non-chord bass such as D in C/D does not belong to C's three inversions.

Nearby positions reduce unnecessary motion

Inversions let the hand stay in the middle register and make upper lines more connected. After root-position C4–E4–G4, second-inversion F at C4–F4–A4 requires only E→F and G→A. First-inversion G at B3–D4–G4 then uses smaller moves than shifting the whole hand to G4–B4–D5.

"Nearest" is a productive practice default, not an aesthetic law. A deliberate leap may expand a phrase or change register. Here the goal is to hear and feel efficient chord changes rather than automatically resetting every chord.

Exercise

Nine C–F–G shapes

Make a three-row table for C, F, and G and three columns for root position, first inversion, and second inversion. Play all nine right-hand shapes for four beats each. Answer in this order every time: chord name, bass, inversion. Then connect C root position → F second inversion → G first inversion → C root position and track the nearest motion in each voice.

In the last score, E3 belongs to C–E–G, so C/E is first inversion. D3 belongs to G–B–D, so G/D is second inversion. Do not call the right hand's lowest pitch the bass while the left hand sounds below it.

Common mistakes

• Symptom: Naming inversion from the first written right-hand note. Correction: Scan from the lowest pitch in both staves, then compare it with root–third–fifth.
• Symptom: Believing each inversion has one spacing. Correction: Rearrange upper notes while retaining bass to create another voicing of the same inversion.
• Symptom: Jumping to root position for every C, F, and G. Correction: Try C root → F/C → G/B and write each voice's motion.

Frequently asked questions

Is second inversion always unstable? Some classical practices treat it in specific contexts; pop and accompaniment frequently use fifth-in-bass chords. Listen within the style.

Does doubling the bass change inversion? No, provided the same chord member remains the lowest pitch and the basic chord content is clear.

Why is G/D not written as a close D–G–B stack? D3 determines the inversion; G4–B4 above it is an open voicing that keeps the bass clear.