The Cadential 6/4

The cadential 6/4 (cad. 6/4) is a dominant embellishment that appears on a strong beat immediately before V or V⁷. Its bass note is scale-degree 5̂ (sol), and above it sit a sixth (3̂, mi) and a fourth (1̂, do) — pitches that sound like a first-inversion tonic triad but function entirely as dissonances above the bass. Because the "tonic" notes are suspensions rather than chord tones, the cadential 6/4 belongs to the dominant, not to I.

The resolution is stepwise and obligatory: the sixth (3̂, mi) falls by step to the fifth (2̂, re), and the fourth (1̂, do) falls by step to the third (7̂, ti — the leading tone). This 6–5 / 4–3 double resolution over the held 5̂ in the bass produces a standard root-position V or V⁷, setting up a strong authentic cadence. The full gesture is often annotated V(6–5)(4–3) to show the stepwise descent of each interval.

Because it looks like I⁶⁄₄ but acts like V, the cadential 6/4 is best understood as an approach to the dominant rather than as an independent chord. It commonly follows strong predominants (ii⁶, IV, or augmented-sixth chords) that prepare the bass arrival on 5̂. The cadential 6/4 is one of the most dependable tools for strengthening a half or authentic cadence, and its predictable resolution makes it a hallmark of Classical-era phrase endings.