C#7sus4 is C#, F#, G# and B — C#7 with the third replaced by the fourth.
It sounds leaning rather than shoving. It keeps the flat seventh’s pull and loses the tritone, so it moves without making a hard cadence.

| C# | F# | G# | B |
|---|---|---|---|
| 1 | 4 | 5 | ♭7 |
Dominant — it points a fifth down, but softly.
Also written C#7sus or C# dominant 7 sus 4. The same chord either way; which spelling you meet depends on who wrote the chart.
C#7sus4 in 2nd inversion puts G# in the bass instead of C#, the 5th of the chord. The notes are the same; what changes is what the bass line does, which is most of why you would reach for it — it lets the lowest voice move by step where the root would have jumped.
One of C#7sus4’s 6 common shapes does this: xx6677.
Start with xxx677 — no barre and only 3 fretted notes. None of the shapes for C#7sus4 uses an open string, so every one of them is movable; the lowest sits at the 2nd fret. 3 of the 6 need a barre. Together they cover the neck from the 2nd fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x44422 | 2nd fret | C#, root position | F# | barred |
| x46474 | 4th fret | C#, root position | G# | barred |
| xxx677 | 6th fret | C#, root position | B | all fretted |
| xx6677 | 6th fret | G#, 2nd inversion | B | all fretted |
| 9-11-9-11-9-9 | 9th fret | C#, root position | C# | barred |
| x-x-11-13-12-14 | 11th fret | C#, root position | F# | all fretted |
The same notes rebuilt from scratch give 5 shell, 12 drop 2 and 9 drop 3 voicings, each on its own page.
Tensions. A shell of C#7sus4, root, third and seventh, leaves a string free, and the tones that belong over it are the 9 (D#) and the 13 (A#).
Voice by voice, C#7sus4 → F#. One voice moves by a semitone, and 2 notes are common to both chords.
| In C#7sus4 | Moves | In F# |
|---|---|---|
| C#, the root | stays where it is | C#, the fifth |
| F#, the fourth | stays where it is | F#, the root |
| G#, the fifth | falls a whole tone | F#, the root |
| B, the flat seventh | falls a semitone | A#, the major third |
In which keys. Every note of C#7sus4 belongs to C# minor (the i), Eb minor (the ♭VII), E major (the vi), F# major (the V), F# minor (the v), Ab minor (the iv), A major (the iii) and B major (the ii).
Every note of C#7sus4 is in C# minor pentatonic, C# blues, C# mixolydian, C# dorian and C# natural minor.
Change one note of C#7sus4 and you have C#sus4 (drop the flat seventh), C#sus2sus4 (the flat seventh becomes a ninth), C#m7 (the fourth becomes a minor third) or C#7 (the fourth becomes a major third).
C#7sus4 is a suspended chord — root and fifth, with a second or fourth where the third would be — or nothing at all. Suspended and power chords on every root.
On C#7sus4’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.