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Stage 4Scales & musicianshipLesson 22 of 70 · Ear & musicianshipNEXT

Inversions, and spelling a triad

A triad has three notes, and any of them can be the lowest. Which one is on the bottom is the triad's inversion — same chord, same name, different bass note, slightly different feel.

The three positions

Take the G major triad — G, B, D:

72 bpm
Same three notes, three arrangements. Bar 1: G on the bottom — root position. Bar 2: B on the bottom — first inversion. Bar 3: D on the bottom — second inversion. It's a G major chord all three times.
PositionBass noteShorthandFeel
Root positionthe root(no figure)most stable — the chord standing up
First inversionthe 3rd6lighter, mobile — very common under a melody
Second inversionthe 5th6/4unstable, wants to resolve — often decorates a cadence

Those numbers

6 and 6/4 are figured bass — an old shorthand where the numbers count intervals above the bass note. A "6" chord has a 6th and a 3rd above the bass; a "6/4" has a 6th and a 4th. Baroque keyboardists read a bass line plus these figures and built the chords on the fly. You just need to recognise the figures when an edition or an analysis uses them.

Why a composer inverts a chord

Two reasons, mostly:

  • to give the bass line a smooth shape instead of jumping around;
  • to keep a particular melody note on top.

The harmony doesn't change — only which note is holding the floor.

Spelling a triad

To spell the triad on any note: stack two thirds, then adjust to the key. On each degree of G major:

72 bpm
The triads on ^1, ^2 and ^3 of G major: G–B–D, A–C–E, B–D–F♯. Each is the note plus the one a 3rd up plus the one a 3rd above that, all drawn from the key's own notes.

Try it

Inversions and spelling

  1. 1
  2. 2
  3. 3
  4. 4

The usual mistake

Treating an inverted triad as a new, different chord. It isn't — a first-inversion G major is still G major, still doing the tonic's job in G. Learn to spot the root even when it's in the middle or on top: find the two notes a 3rd apart at the bottom of the stack, and the lower of those is usually the 3rd, which means the root is the note just below it in the chord.