Chord Theory 3: Extended Chords

In the previous chords post we learned about seventh chords. Today we are going to add even more notes on top to create extended chords.

Natural Tensions

Adding notes above the seventh is as easy as extending the chord formula of seventh chords. The maj7 chord formula is 1, 3, 5, 7 so the next logical notes, would be 9, 11, and 13. Notes such as these, that are above the seventh, are known as ‘tensions’.

There is no need to add tensions above the thirteenth because, as can be seen in the image below, the fifteenth is the same note as the root, the seventeenth is the same as the third etc.

Maj9 Chords

Constructing a maj9 chord is as easy as starting with a basic maj7 chord formula and then adding a ninth on top. For example, building a Cmaj9 chord would mean starting with a Cmaj7 chord (C E G B) and putting a 9th on top. Our knowledge of intervals and scale degrees tells us that a 9th above C is D, so a Cmaj9 chord will be C E G B D.

Chord Name	Formula	Actual Notes in C
Maj7	1 3 5 7	C E G B
Maj9	1 3 5 7 9	C E G B D

Maj11 Chords

Adding an 11th on top of a maj9 chord gives us a maj11 chord. For Cmaj11, this means starting with a Cmaj9 (C E G B D) and then adding an F on top. However, bear in mind that maj11 chords are very rare due to the unpleasant dissonance created by the 11th clashing with the 3rd of the chord – in a Cmaj11 this would be the F clashing with E.

Chord Name	Formula	Actual Notes in C
Maj9	1 3 5 7 9	C E G B D
Maj11	1 3 5 7 9 11	C E G B D F

Maj13 Chords

Theoretically, a maj13th chord would be a maj11 with a 13th added on top. However, due to the dissonance associated with the 11th, it’s usual to omit it. This means that the real-world formula for a maj13 chord would be 1 3 5 7 9 13.

Chord Name	Formula	Actual Notes in C
Maj13	1 3 5 7 9 13	C E G B D F A

Extended Minor Chords

Adding extensions to min7 chords follows the same procedure as for maj7 chords. This means that:

• Adding a ninth to a min7 chord creates a min9 chord
• Adding an eleventh to a min9 chord creates a min11 chord
• Adding a thirteenth to a min11 chord creates a min13 chord

It is usual to include the eleventh in minor type chords, as there is no ‘clash’ between the eleventh and the minor third (the notes Eb and F in a Cmin chord). Therefore, while maj11 chords typically sound disagreeable, min11 chords sound perfectly pleasant. It also means that the eleventh is included in the formula for min13 chords.

Chord Name	Formula	Actual Notes in C
Min9	1 b3 5 b7 9	C Eb G Bb D
Min11	1 b3 5 b7 9 11	C Eb G Bb D F
Min13	1 b3 5 b7 9 11 13	C Eb G Bb D F A

Extended Dominant Chords

Adding extensions to dominant chords is essentially the same as with major and minor chords. However, since dominant chords have a major third, the eleventh will ‘clash’. Dominant 11 chords are therefore rare (in a C11 the F will clash with the E), and the eleventh should also be omitted from dominant 13 chords, for the same reason.

Chord Name	Formula	Actual Notes in C
9	1 3 5 b7 9	C E G Bb D
11	1 3 5 b7 9 11	C E G Bb D F
13	1 3 5 b7 9 13	C E G Bb D A

Other Extended Chords

The most commonly extended chords are based on the maj7, min7 and dominant 7 type chords, although it is also possible to extend min(maj)7 chords and min7b5 chords. Extensions cannot be added to diminished and augmented chords (not normally, anyway), because of the symmetrical structure of these chords – I’ll explore symmetrical chords (and scales) thoroughly in a coming post.

Because min(maj)7 chords and min7b5 chords are both minor-type chords, we are free to include the eleventh without creating a clash.

The first table shows the extensions for min(maj)7 type chords.

Chord Name	Formula	Actual Notes in C
min(maj)9	1 b3 5 7 9	C Eb G B D
min(maj)11	1 b3 5 7 9 11	C Eb G B D F
min(maj)13	1 b3 5 7 9 11 13	C Eb G B D F A

This table shows the extensions for min7b5 type chords.

Chord Name	Formula	Actual Notes in C
min9b5	1 b3 b5 b7 9	C E G Bb D
min11b5	1 b3 b5 b7 9 11	C E G Bb D F
min13b5	1 b3 b5 b7 9 11 13	C E G Bb D F A