Ultimate Guitar Lesson

V. Extended and Altered Chords

These are divided into two parts.
Extensions are notes above the 7th: 9ths, 11ths, and 13ths.
All extensions are major or perfect unless an alteration is specified.

Gmi9 - G Bb D F A Gmi7(b9) - G Bb D F Ab
1 b3 5 b7 9 1 b3 5 b7 b9

Extended chords theoretically include all the possible extensions up to the one listed.

Cmi13 - C Eb G Bb D F A
1 b3 5 b7 9 11 13

When you say "mi13" be prepared to hear any or all of these notes.

That was minor. Now let us extend a dominant chord.

F13 - F A C Eb G Bb D
1 3 5 b7 9 11 13

That’s right. The perfect 11th of F is Bb.

The common practice when including the 11th on a major or dominant chord is to remove the 3rd so it doesn’t clash.
If you want to keep the 3rd for your own perverted reasons you can raise the 11th, as shown in this major chord.

Amaj13 A C# E G# B D F# A C# E G# B D# F#
  1 3 5 7 9 11 13 1 3 5 7 9 #11 13
  ‘in theory’ ‘in practice’

A chord may be stated and any desired alterations specified: G7b9, Ebmi7#5, A7sus4b9, Cbmaj7#5, Gb7b13, etc.

Rarely, parentheses are needed to keep you from accidentally changing the root of a chord.

A(b5) - A C# Eb Ab5 - Ab Eb (power chord)
  1 3 b5 1 5
Gb9 - Gb Bb Db Fb Ab G(b9) - G B D Ab
  1 3 5 b7 9 1 3 5 b9

Dominant chords are the ones most often altered.

E7(alt) = E7b9#9b5b13 - E G# Bb D F F## C
1 3 b5 b7 b9 #9 b13

When you see the “alt” chord symbol you can use any of the above notes to your taste.

Do not include any unaltered extensions unless a mixture is specified.
Here is a common natural-extension-mixed-with-altered-extension chord.

F13b9 - F A C Eb Gb (B) D
1 3 5 b7 b9 (#11) 13