How Chord Symbols Work

I’ve seen this subject trip up a lot of people. There are a lot of rules, exceptions, and disagreements. In addition, musicians tend break the rules or make up their own rules, spoken or unspoken.

For example, the chord G11 technically contains the following notes: G, B, D, F, A, C. But everyone just leaves out the B (3rd). Another example, G13 technically contains the notes: G, B, D, F, A, C, E. But in practice no one plays E (11th).

To complicate matters further, there are conflicting ways of naming chords. And what’s implied isn’t always what someone means when they write the chord symbol. For example the following are all technically acceptable to represent the notes: G, B, D#, F:

• Gaug7
• G7(b13)
• G7+
• G7(#5)

Also, I think most people map the interval numbers to the Major Scale (at least that’s how I was taught, maybe I’m the exception). However, you then run into having to explain why the 7 in C7 is Bb and not B-natural. As you’ll see below, I recommend mapping the intervals to the Mixolydian Scale (C Major Scale starting on the 5th note). Or not thinking of scales at all (i.e. 7 = dom7 by definition).

Below are my thoughts on how to approach naming chords and their relationships to intervals. (#) should be read to mean “raised” and (b) should be read to mean “lowered” (e.g…1 b3 #5 denotes a lowered 3 and a raised 5). Though it’s not comprehensive, for me, it’s the most consistent in terms of rules and common practice.

Mapping Intervals to a Scale

As mentioned above, mapping intervals to the Mixolydian scale is much cleaner. Using the Mixolydian scale as “home-base” provides an accurate picture of what’s happening between chord symbols and intervals:

• 1 = Root
• 2 = Maj 2nd
• 3 = Maj 3rd
• 4 = Perfect 4th
• 5 = Perfect 5th
• 6= Major 6th
• 7 = Dominant 7th

And, of course, it’s understood that you can interchange 9 for 2, 11 for 4, and 13 for 6.

C Major Scale starting on G (Mixolydian)

Basic Triads

1. Major Triad (1 3 5) = G
2. Minor Triad (1 b3 5) = Gm
3. Augmented Triad (1 3 #5) = G+
4. Diminished Triad= (1 b3 b5) = Gº

Sus and 2 Chords

Sus = play the 4th and no and no 3rd.
Sus 2 = play the 2nd and no 3rd
2 = Add 2 or 9

• 1 4 5 = Gsus
• 1 4 5 7 9 = G9sus
• 1 2 5 = Gsus2
• 1 3 5 9 = G2 or G(add9)

Dominant 7th Chords

Major triad plus a dominant 7th. In practice, the implied 11 is usually omitted.

• (1 3 5) 7 = G7
• (1 3 5) 7 9 = G9 (the 7th is implied)
• (1 3 5) 7 9 11 = G11 (the 7th and 9th are implied)
• (1 3 5) 7 9 11 13 = G13 (the 7th, 9th, and 11th are implied)

Minor 7th Chords

Minor triad or a diminished triad plus a dominant 7th.

• (1 b3 5) 7 = Gm7
• (1 b3 5) 7 9 = Gm9 (the 7th is implied)
• (1 b3 5) 7 9 11 = Gm11 (the 7th and 9th are implied)
• (1 b3 5) 7 9 11 13 = Gm13 (the 7th, 9th, and 11th are implied)
• (1 b3 b5) 7 = Gm7(b5)
• (1 b3 b5) 7 9 = Gm9(b5) (the 7th is implied)

Major 7th Chords

Major or minor triad plus a Major 7th. No 11s are implied. The #7s may look jarring. Remember it just means a “raised 7”.

• (1 3 5) #7 = GMaj7
• (1 3 5) #7 9= GMaj9 (the 7th is implied)
• (1 3 5) #7 9 13= GMaj13 (the 7th and 9th are implied)
• (1 b3 5) #7 = GmMaj7
• (1 b3 5) #7 9 = GmMaj9 (the 7th is implied)

Altered Dominant 7 Chords

(1 3 7) + any combo of raised or lowered 5s, 9s, 11s, 13s. Use (b) and (#) to designate lowing and raising of intervals, not (+), minus (-) or “aug”.

• (1 3 7) 5 #9 = G7(#9)
• (1 3 7) #5= G7(#5)
• (1 3 7) #5 #9 = G7(#5#9)
• (1 3 7) 5 b9 13 = G13(b9)