Over the years there have been various different methods used to write chord symbols. Jazz evolved from using simple harmony back in the old days to quite complex harmony that was made popular by the bebop innovators, which used upper extensions (9ths, 11ths and 13ths etc.), and chromatic alterations (b5, #11 etc.).
In early music triads were often used so a chord symbol could be as simple as C (for a C major triad) and Cm (for a C minor triad).
Early sheet music started to include chord symbols, but very often they were written with banjo players in mind and (rightly or wrongly) were simplified. Serious jazz composers needed to invent symbols rather than notation as it was much more conducive to the creative and spontaneous process of jazz improvising.
Chord symbols can work best when they are as short as possible, otherwise sheet music can become very cluttered, but be careful they aren’t confusing, especially when written by hand in a hurry.
Common chord types with alternative symbols
- The symbols in red are recommended as some of the others can be confusing (especially “-” for minor and “alt”> for altered forms of 9 and 13.
- The triangle symbol can be useful for major 7 (Δ or Δ7) when in a hurry, but be careful as it can sometimes look like a badly drawn
- The capital
Mfor major 7 can also be confused for lower case “m”>.
|C major 7||Cmaj7||Cma7||CΔ or CΔ7||CM7|
|C minor 7||Cm7||Cmin7||C-7||–|
|C minor major 7||Cm maj7||Cmin ma7||C – Δ7||C –|
|C half diminished||Cø7||Cm7 b5||Cmin7 b5||–|
|C diminished (7)||Co (7)||C dim (7)||–||–|
|C7 suspended 4th||C7 sus4||–||–||–|
|C7 augmented||C+7||C7 aug (C7+)||C7+5||–|
|C7 flat 5th||C7 b5||C7 -5||–||–|
|C7 #11||C7 #11||C7 +11||–||–|
|C7 flat 9th||C7 b9||C7 -9||–||–|
|C7 sharpened 9th||C7 #9||C7 +9||–||–|
|C7 flat 10th||C7 b10||C7 -10||–||–|
|C7 flat 9th flat 13th||C7 b9 b13||C7 alt||–||–|
|C7 flat 10th flat 13th||C7 b10 b13||C7 alt||–||–|
|C13 sharp 11th||C13 #11||C13 +11||–||–|
* C11 in many cases omits the 3rd because the 11th often functions as a suspension. This is why we can sometimes think of it as a Gm7/C. It can be argued that if the 3rd is present the sound is quite discordant. However when voicing the chord it can be effective in inside parts to include the 3rd immediately next to the 11th for an interesting crunch, or to voice it a major 7th above the 11th.