Sus chords

”Sus” stands for suspension and what happens in these chords are that the third (the second note) are being replaced with either a major second or a perfect four. Then it is replaced with a major second the chord name is sus2, and then it is replaced with a perfect four the chord name is sus4. There are also extended suspended chords.

See diagrams of sus chords:

C sus D sus E sus F sus G sus A sus B sus

C7 sus D7 sus E7 sus F7 sus G7 sus A7 sus B7 sus

Theory

As mentioned above, there are several categories of suspended chords, but in most cases it is either a sus2 or a sus4.

Comparing the C major Chord with Csus2 and Csus4:

C: C – E – G
C chord

Csus2: C – D – G
csus2 chord

Csus4: C – F – G
csus4 chord

Formulas

The formulas are 1 - 2 - 5 (sus2) and 1 - 4 - 5 (sus4).

Other sus chords

Beside the common sus2 and sus4 chords there are more categories. A seventh or a ninth chord, for example, could be suspended.

Let us compare a C7 chord with C7 sus chords:

C7: C – E – G – Bb
C7sus2: C – D – G – Bb
C7sus4: C – F – G – Bb

Let us also compare a C9 chord with a C9sus4 chord:

C9: C – E – G – Bb – D
C9sus4: C – F – G – Bb – D

Among these extended suspended chords, the ninth suspended chord are the less common. C9sus4 is more commonly known as C11 (to be exact, it is an inverted C11 without a major third).

Alternative chord names

Besides the standard sus4/sus2 names, the annotation C4, D4, E4 and so forth can occur and often together with C3, D3, E3 and so forth (meaning a sequence from sus to major).