Available Tensions · Jazz Wiki

Available tensions are the notes above the basic 7th chord — the 9th, 11th, 13th, and their alterations — that a player can stack on top without smearing the chord’s identity. They exist because of a simple acoustic fact: a tension a whole step above a chord tone sounds like color, while one a half step above sounds like a mistake. Knowing which extensions are “available” on which chord is what separates a voicing that sounds rich from one that sounds muddy.

The whole-step rule and why it works

Every extension lands somewhere relative to the chord tones already present — the root, 3rd, 5th, and 7th. If that extension sits a whole step above the nearest chord tone below it, the ear hears it as an added color riding on top of a stable structure. If it sits only a half step above a chord tone — especially the half step created against the 3rd or 7th — it clashes hard enough to obscure the chord’s quality, which is why theorists call it an avoid note. This is really just consonance and dissonance applied one octave up: the same interval logic that governs chord tones governs tensions, just transposed.

The 3rd and 7th are the guide tones that tell your ear whether a chord is major, minor, dominant, or half-diminished, so tensions that clash with them are the ones to treat carefully. The root and 5th matter less, which is exactly why dominant chords — already built on a dissonant tritone between 3rd and 7th — can absorb almost any alteration without losing their identity.

What’s available on each chord quality

Cmaj7 (C–E–G–B): available 9 (D), ♯11 (F♯), 13 (A) — avoid natural 11 (F), a half step above E
G7 (G–B–D–F): available 9, ♭9, ♯9, ♯11, 13, ♭13 — dominant chords tolerate nearly everything
Dm7 (D–F–A–C): available 9 (E), 11 (G) — 13 (B) context-dependent: it forms a tritone with the ♭3 (F) that makes the ii chord sound like a V7
Cm7♭5 (C–E♭–G♭–B♭): available 9 (D), 11 (F), ♭13 (A♭) — ♭9 (D♭) avoided, a half step above the root

Stacking the guide tones with the available tensions shows how cleanly they ride above the chord: on Cmaj7, D (9), F♯ (♯11), and A (13) all sit a whole step above the nearest chord tone below them.

Tensions on Cmaj7 — available vs. avoid

A13

F11

tensions above the 7th

D and A each ride a whole step above the chord tone beneath them, so they read as color; F sits only a half step above the 3rd, so it is the avoid note — raise it to F# and it becomes available

A dominant chord absorbs alterations the same way — here G7 moves from its plain chord tones to a full set of altered tensions (♭9, ♯9, ♯11, ♭13):

On a Major Seventh Chord the natural 11 sits a half step below the major 3rd — an unmistakable clash — so it’s raised to a ♯11, borrowed from the Lydian Mode, giving that bright, floating sound so many pianists reach for instead of plain major. On a Dominant Seventh Chord, because the tritone is already doing the dissonant work, ♭9 and ♯9 (drawn from The Altered Scale or Lydian Dominant depending on context) are not just tolerated but prized for their edge. Minor 7th chords get 9 and 11 freely from Dorian Mode, but the 13 is dicey because it forms a tritone with the ♭3 — on a functioning ii chord it blurs the line into the coming dominant, so treat it as available mainly in modal writing. The Half-Diminished Chord behaves like a minor 7 with a lowered 5th, so its available tensions (9, 11, ♭13) follow the same logic — with the caveat that the natural 9 is a modern softening; the plain Locrian sound offers only a ♭9, a half step above the root, which most players avoid.

Reading tensions off the scale, not memorizing them

In practice, most players don’t memorize these lists chord by chord — they think in terms of Chord-Scale Theory: pick the scale that matches the chord’s function (Dorian for a diatonic ii, Lydian dominant for an altered V7 substitute, the major scale itself for a static I), and every non-chord-tone in that scale that lands a whole step above a chord tone is fair game. This is also how Chord Alterations get chosen on dominant chords: ♭9, ♯9, ♯11, and ♭13 aren’t random spice, they’re the notes of the altered or Lydian-dominant scale, selected because they clash productively with the root and 5th while leaving the guide tones untouched. When comping, this thinking shows up directly in Rootless Voicings and Upper Structure Triads, both of which are really just efficient ways to stack available tensions on top of the guide tones without playing every note in the chord.

♫ Listen

Bill Evans Trio — “Autumn Leaves” (Portrait in Jazz, 1959): the opening piano voicings stack 13ths and ♯11s over rootless left-hand shells — hear how the extensions ride cleanly above the 3rd and 7th without clouding the harmony.
Herbie Hancock — “Maiden Voyage” (Maiden Voyage, 1965): quartal voicings built from stacked 4ths pile up minor 11th and 13th sonorities over the modal vamp, showing how far the available-tensions palette opens up once you leave functional harmony behind.