Csus4: C Suspended 4th Piano Chord

Root position: either hand, fingers low note to high
Hand	Notes	Fingers
Right	C, F, G	1-3-5
Left	C, F, G	5-3-1

Scale degree, note, and interval measured from the root.
Degree	Note	Interval from root	Semitones
1	C	Perfect unison	0
4	F	Perfect fourth	5
5	G	Perfect fifth	7

Construction

C Suspended 4th = Root + Perfect 4th + Perfect 5th = C, F, G

Note	Interval	Degree
C	Root	1
F	Perfect 4th	4
G	Perfect 5th	5

Fingering

Note	Key color	Right hand	Left hand
C	white	thumb (1)	little finger (5)
F	white	middle finger (3)	middle finger (3)
G	white	little finger (5)	thumb (1)

Right hand: thumb (1) on C, middle finger (3) on F, little finger (5) on G.

Left hand: little finger (5) on C, middle finger (3) on F, thumb (1) on G.

C Suspended 4th Inversions

Root position
C – F – G
1st inversion (Csus4/F)
F – G – C
2nd inversion (Csus4/G)
G – C – F

Key Signature

A Suspended 4th chord is built from symmetrical or ambiguous intervals, so it doesn't belong to a single key and has no key signature of its own.

Chords in the Key of C Major

These are the triads built on each degree of C Major:

I — C Major (major)

Degree	Numeral	Chord	Quality
1	I	C Major	Major
2	ii	D Minor	Minor
3	iii	E Minor	Minor
4	IV	F Major	Major
5	V	G Major	Major
6	vi	A Minor	Minor
7	vii°	B Diminished	Diminished

Scales That Include the C Suspended 4th

C Major (I)
Ab Major (iii)
Eb Major (vi)
Bb Major (ii)
F Major (V)
A Minor (III)
D Minor (VII)
G Minor (iv)

Same Notes, Other Names

The notes C – F – G aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell:

F Suspended 2nd→

C Suspended 4th : Frequently Asked Questions

What notes are in Csus4?

Csus4 contains C, F and G. The formula is 1, 4, 5.

How do you play Csus4 on piano?

Play C, F and G together. Right hand fingers 1, 3, 5; left hand 5, 3, 1. Every note is a white key.

What are the inversions of Csus4?

3 positions: root position C F G, Csus4/F, Csus4/G.

What is the difference between Csus4 and C7sus4?

Adds B♭. 3 of the notes are shared.

What is an easy Csus4 for small hands?

The root and third only voicing, C3 F3, spans 5 semitones or about 69 mm.

What are the frequencies of Csus4?

From C3 at A440 in 12-TET: 130.81, 174.61, 196.00 Hz.

What is the set class of Csus4?

Prime form (027), Forte 3-9, interval vector <010020>.

How do I transpose Csus4 to another key?

Keep the 1, 4, 5 formula on the new root. C♯sus4 is C♯, F♯, G♯; D♭sus4 is D♭, G♭, A♭.

C Suspended 4th in detail

Exact

Every pitch class is present and nothing outside the chord is added.

Type	Notes	Semitones	Span	Omissions and additions	Set relation
Close, root position	C3 F3 G3	7	96 mm	none	identical
Close, first inversion	F3 G3 C4	7	96 mm	none	identical
Close, second inversion	G3 C4 F4	10	138 mm	none	identical
Open, fifth on top	C2 G2 F3	17	234 mm	none	identical

Reduced

A subset of the pitch classes: the identity is incomplete rather than altered.

Type	Notes	Semitones	Span	Omissions and additions	Set relation	Fit
Root and third only	C3 F3	5	69 mm	omits G	subset

Spans are measured centre to centre at a 165 mm octave (standard keyboard geometry).

Position	Bass note	Notes in order	Figured bass	Semitones	Span
Root position	C	C3, F3, G3	5/3	7	96 mm
First inversion: Csus4/F	F	F3, G3, C4	6/3	7	96 mm
Second inversion: Csus4/G	G	G3, C4, F4	6/4	10	138 mm

One position per chord tone in the bass. Spans are for close position: voiced inversions appear under Voicings.

Change one note

Chords a single note away, and what moving that note does.

Chord	Change	Formula	Common tones
C7sus4	adds B♭	1 4 5 ♭7	3
C	F becomes E	1 3 5	2
Cm	F becomes E♭	1 ♭3 5	2
Csus2	F becomes D	1 2 5	2
Cmaj7	F becomes E, B	1 3 5 7	2
C7	F becomes E, B♭	1 3 5 ♭7	2
Cm7	F becomes E♭, B♭	1 ♭3 5 ♭7	2
CmMaj7	F becomes E♭, B	1 ♭3 5 7	2
C6	F becomes E, A	1 3 5 6	2
Cm6	F becomes E♭, A	1 ♭3 5 6	2
Cadd9	F becomes E, D	1 3 5 9	2
Cdim	F, G becomes E♭, G♭	1 ♭3 ♭5	1

Frequencies

Note	MIDI	Frequency
C3	48	130.81 Hz
F3	53	174.61 Hz
G3	55	196.00 Hz

Reference pitch A440, 12-TET, close root position.

Set theory: prime form, Forte number, interval vector

Absolute pitch class set: {0, 5, 7}
Normal order: [5, 7, 0]
Prime form: (027)
Forte number: 3-9
Interval vector: <010020>

Pair	Interval	Semitones	Interval class
C to F	Perfect fourth	5	5
C to G	Perfect fifth	7	5
F to G	Major second	2	2

Where these facts come from

Every value on this page is derived from the note formula for a suspended 4th applied to the root C, using standard music theory. Nothing here is hand-entered per chord, so the notes, intervals, inversions and frequencies cannot drift out of agreement with each other. Pitches assume 12-TET at A440.

C Suspended 4th

Fingerings

C Suspended 4th: notes and degrees