Jazz chords: shell shapes [rough]


How to decode chordal parts for basically anything in the Real Book…

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• Basic approach •

While jazz is notorious for complex harmony, the foundations are very concise (especially on guitar). To decipher any Real Book progression (or basically any other chord chart), you only need to answer three questions:

  • Root movement: how does the ‘main note’ shift around?
  • Chord character: what ‘chord type’ is being asked for?
  • Voicing selection: which physical shapes will work best?

e.g. for the 4-bar sequence ‘Am7 | Cmaj7 | Bm7 Bb7 | Am7’:

  • Roots: Am7 | Cmaj7 | Bm7 Bb7 | Am7
  • Chords: Am7 | Cmaj7 | Bm7 Bb7 | Am7
  • Shapes: see below for the menu…

The biggest misconception here is that the playing is the hard part: in fact, the main barrier to entry is the ‘chordal decoding’ process (i.e. ‘wtf do all these letters and numbers mean?’). But if you rote-learn a fairly small amount of info, it all becomes intuitive quickly…

• 1: Root movement •

Bass path: firstly, work out which path the ‘first letters’ of the chords spell out, and just play these as single notes using only the 6str and 5str – we’ll build the full chords on top of these. It’s worth rote-learning the 6/5str note names (n.b. don’t bother doing this for any other strings):

• 2: Chord classification •

Families: For all the abstruse symbolic language of jazz, you can summarise virtually any chord into one of just a few ‘families’ (=’major, minor, dominant, others’). Then, you only need handful of ‘shell shapes’ (mini 3-string voicings) to cover any of them. Here is a brief ‘taxonomy’ for which names go into which families:

  • Majors: maj7, maj9, maj11, 6, 6/9, maj7(#11)
  • Minors: m, m7, m9, m7(b5), m6, m7(11)
  • Dominants: 7, 9, 11, 13, 7(b9), 7(#9), 7(b5)
  • [Others: dim, dim7, aug(7), sus2, sus4, etc]

The shapes are designed to be fully moveable – so avoid plucking the open strings by default (although if they fit then add them in!). The best practice here is to just flick through the real book, look at random chords, and ask ‘ok which family?’. Sometimes you’ll hear less fluent/desirable clashes even when using these voicings – just see how they pan out and adjust by ear, not by theory.

• 3: Voicing choice •



• Formatting quirks •

And a few oddball pointers:

  • Sharps/flats: sharp (#) = raise by one semitone, and flat (b) = lower by one semitone (e.g. A# = Bb). Jazz prefers flats.
  • Shape symbols: maj7 chords are sometimes written with a triangle (CΔ7). Also, a long dash means minor (C7), a circle means full diminished (Cº7), a crossed out (‘halved’) circle means half-diminished (Cø7), and a plus means augmented (C+). These were apparently introduced by Trane, and have a playful hidden logic behind them.
  • Inversions: if you see a slash in the name (e.g. ‘Bm7/A‘), this means that the voicing’s lowest note isn’t the root. Read everything before the slash like a normal chord name – and whatever comes after it is the new bass note (‘Bm7/A’ = ‘Bmin7, but with an A in the bass). These are pretty optional in jazz, so you can usually just ignore the slash onwards.
  • Formatting: brackets are often put around any extra notes which don’t fit the chord family so neatly (e.g. ‘Cm(maj7)‘ means ‘Cmin, but with an added major 7’). Superscripts are just for optional visual clarity (e.g. ‘C-9‘ = ‘C-9’) – and you might occasionally see things like ‘Cmaj9(no5)‘, which just means ‘remove the 5th’.

There are other irregularities (e.g. the Real Book has a few errors, and also many versions are in somewhat messy handwriting). Main thing is not to worry about them…the gaps will fill themselves in as the ear develops.

• Bonus: chord formulas •

Chord construction: not essential, but your exploratory curiosity will naturally lead towards this area. This is what the chord names actually mean – they’re basically a ‘shorthand’ for the unique recipe of ‘scale tones’ you use to make them.

  • e.g. ‘Cmaj7’ means ‘start at C, then add the ingredients for a maj7 chord’ – which equates to ‘take the C major scale, then use its 1st, 3rd, 5th, and 7th notes

A sharp (#)

Majors: based on tones ‘1-3-5’

  • maj (triad): 1-3-5
  • maj7: 1-3-5-7
  • maj9: 1-3-5
  • maj11: 1-3-5
  • 6: 1-3-5
  • 6/9: 1-3-5
  • maj7(#11): 1-3-5

Minors: based on tones ‘1-b3-5’

  • min (triad): 1-b3-5
  • m7: 1-b3-5-b7
  • m9: 1-b3-5-b7-9
  • m7(b5): 1-b3-b5-b7 (technically a ‘half-diminished’)
  • m6:
  • m7(11):

Dominants: based on tones ‘1-3-5-b7’

  • 7: 1-3-5-b7 (yeah…a b7 not a ‘7’)
  • 9:
  • 11:
  • 13:


  • Dominants: 7, 9, 11, 13, 7(b9), 7(#9), 7(b5)
  • [Others: dim, dim7, aug(7), sus2, sus4, etc]

Ambiguous sevens: for reasons unknown, a ‘7th’ chord (e.g. A7) actually has a ‘flat 7’


A lot of my jazz harmonic knowledge has come from just thinking ‘oh, well the note on this string changed…


A few general learning principles:

  • Listen to lots of different music: feed the brain with good sounds
  • Train the ear: this gives you the ‘toolbox’ to teach yourself any style
  • ‘Sing inside’ as you play: music is about emotions, not finger muscles
  • Experiment freely: constantly create your own patterns & variations
  • Enjoy it! Find fun in improvement…then mastery is no struggle

George Howlett is a London-based musician and writer. I play guitar, tabla, and santoor, loosely focusing on jazz, rhythm, and global improvisation. Above all I seek to enthuse fellow sonic searchers, interconnecting fresh vibrations with the human voices, cultures, and passions behind them.


Recently I’ve worked long-term for Darbar, Guitar World, and Ragatip, and published research into tuning and John Coltrane’s raga notes. I’ve written for Jazzwise, JazzFM, and The Wire, and also record, perform, and teach in local schools. Site menu above, follow below, & get in touch here!