Answers to the question How do they decide the key? point out how useful it is for a jazz musician to be able to play a piece in any key.

So, in jazz, why does sheet music give chord symbols with absolute, not relative, roots? Chord symbols with absolute roots reinforce the association with the particular key represented by the notes, and make it harder for the player to learn the chord sequence in other keys. (At any rate, up to the point where the player has memorised the piece and thus doesn't need the sheet music at all.)

Traditional chord notation (I, V etc) is relative, so absolute-root chord notation represents a change from tradition.

A theoretical discussion of a particular chord progression (independent of what pieces use it) may use relative chord notation, but I'm thinking here of the notation of the chords for particular pieces.

  • The melody is the essential feature of a tune, and it is easier to relate a melody written on the staff to chords written above the staff when they are not hidden behind "relative" names. – ex nihilo Feb 17 '18 at 12:51
  • Why does the question specify jazz? It's applicable across the board. Transposing is important for almost any genre. – Stinkfoot Feb 18 '18 at 20:18
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    @Stinkfoot This question was a propos a question about jazz. It could, I suppose also apply to pop/rock. But it's relevant only where sheet music gives chord symbols. In voice & piano, the pianist needs to read from the song's high/medium/low voice edition (whichever suits the singer) if there's a choice. – Rosie F Feb 19 '18 at 7:31
  • @RosieF … or sight transpose, if capable. Many are. – phoog Feb 22 at 16:14

"Chord symbols with absolute roots [...] make it harder for the player to learn the chord sequence in other keys." I do not agree with your premise. Why would that be the case? Imagine you have a very simple piece with chords I IV V. In order to be able to play that piece in all keys, you need to know the IV and the V in all keys. Now if you do know that, why would it then be harder to play the progression F Bb C in another key? You know that Bb and C are the IV and the V, respectively, (because you would need to know that in any case), and you know the IV and V in all other keys.

Luckily not all pieces are that simple. If you have modulations or tonicizations, using relative roots can get quite messy, and absolute chords are easier to read for most people, even if you need to transpose on the spot. Have you tried to write a more complex piece with relative roots?

Apart from that, nowadays I see more and more musicians at jazz sessions use software (like ireal pro or fakebook pro) that transposes the pieces to any key they like, so people are not that afraid anymore of singers who ask the band to play pieces in unorthodox keys.

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    Haven't met 'fakebook pro' et al, but feel they're a bit of a cop out. Any decent player - particularly a jazzer - should be able to play something in any key.. in my book anyway! – Tim Feb 17 '18 at 12:30
  • @Tim Pros in all industries use the tools available to them. I can't recall the last time I saw a jazz combo playing a corporate gig (and in my town, there are lots of jazz combos playing lots of corporate gigs) where at least one of the musicians wasn't using an iPad for the lead sheets. – Todd Wilcox Feb 17 '18 at 12:44
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    @ToddWilcox - I'm working with guys all the time now, that use them. However, the vast majority use the printed sheet on screen - not to facilitate changing key. It's just easier for them to turn the pages! – Tim Feb 17 '18 at 13:02

I guess that when a composer comes up with a new number, he'll have a key in mind - the key he's playing it in. This becomes the original key, and gets written down as such.

Most classics - standards - have an original key. Summertime - Am., Georgia - F, etc, which are well known to jazzers. They sometimes need changing, usually for vocals, but are probably still best written in 'a key'. NNS works pretty well, although it wasn't really designed for jazz music.

I feel that most decent players will (or should be able to) transpose to any of the other 11 keys at will, so knowing the 'original' will be good enough. And those who can't or won't, well, there's a key ready waiting for them...

  • This is the right answer - quite simple. Either it was written originally in that key, or a very popular version was played/recorded in the key they print up. We write music in a specific key, not with Nashville numbering and that's what gets published. – Stinkfoot Feb 18 '18 at 20:15

Because jazz chord symbols are primarily an aid to performance, not an aid to analysis. The immediate requirement is knowing WHAT notes to play, not knowing whether it's I, IV, V etc. in any particular key.

OK, there's 'Nashville numbers' which ARE relative. It suits the generally simple harmonies of country music well, and certainly enables easy transposition. But I don't think you'd want to approach 'Giant Steps' through Nashville notation!

  • This strikes me as the right answer. In some cases (Giant Steps being an extreme example), it's simply impossible because there is no single root. In cases where it is possible, it's easier for the brain to see Bb7 than bVII7, which helps when gigging. A third reason is that seeing the chord helps recollect alternative scales/modes to use when improvising. If I see Bb7, I might think "oh, I could play Lydian dominant here, which is from the F melodic minor parent scale." That's harder to do when presented with IV7 or bVII7. Finally, it's easy enough to infer the function on the spot. – jdjazz Feb 22 at 1:25
  • Sounds reasonable. Sightreading is hard enough as it is, why add another layer of abstraction that requires another mental operation to figure out where to put your fingers? – Richard Metzler Feb 22 at 7:18
  • It's interesting to compare these with figured bass another absolute system which like the jazz chord symbols was a performance aid or notation short hand, but not an analysis tool. This really does seem the most insightful distinction. – Michael Curtis Feb 22 at 14:55

There's two parts to this answer I think:

  1. How did it happen?
  2. Wouldn't it be better to have relative notation?

The first answer would be... well it evolved this way, evolved out of musical practice, evolved out of the first realbook. It's worth remembering that the realbook came long after the prime time of bebop and back then everything was played and learned by ear.

The second answer, it definitely would not be better for analysis and getting your way around the tune. A typical jazz tune has many key centers so deciding what would be I for the whole piece is arbitrary. And then if you pick anything the whole notation would be muddled up across key changes and will not represent how players think about the tunes. Jazz players use relative notation but in a different way - they see Autumn Leaves as a string of II-V-I modulated around the cycle of fifths. And this is actually useful.


The root notes often are organized in terms of a semi-melodic bass line which is not as much related to the chord at the moment but rather to surrounding notes of the bass line.

The baroque tradition of writing figured bass works by actually spelling out the bass line and writing all chords in relation to the bass line rather than core harmonies. That makes the actual harmonic progression more opaque (of course, experience and practice make a whole lot of difference then again) than typical Jazz notation.

For better or worse, writing down the bass line in more absolute terms makes it easier to work and comprehend it independently of the actual chords. Other reference frames would be thinkable but would likely make it harder for someone actually playing a bass instrument to crank out the respective line.

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    By 'root notes', I think the OP was referring more to the actual names of chords, rather than notes played by the bass, so this is coming over as unclear. – Tim Feb 17 '18 at 16:42
  • @Tim You've understood me correctly. A player wanting to know the composer's intended bass line (rather than improvising one) could just read the notes. – Rosie F Feb 18 '18 at 7:11

My answer is pure speculation:

  • most jazzer were of aren’t educated in western music theory as roman numericalb notation or solfege or even fingered bass.

  • guitarists and bass player can transpose easily from moving a bend or half tone higher or lower.

  • the chord progressions in jazz are to a high % level interpreted by iim7 V7 I, the jazz cadence, the subdominant cadence I I7 IV IVm I and the tritonus substitution and a few other clauses.

  • the notation of 9,11,13 chords would be difficult to read (especially their inversions

  • many jazz musician are unconsciously analyzing (as a conditioned reflex) the music, chords and harmony. They even don’t need to have sheet music or alead sheet and can transpose the piece in any key.

  • for improvisation most jazz musician of any instrument have their riffs and licks that are adaptable to any tune and a jazzer is used to transpose the licks in all keys.

So the absolut notation becomes to him the same as a relative notation.

(I prefer or need still a lead sheet with both, absolute and relative notation of the chord-progression - this is the basic for transposing in to other keys.)

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