Jazz Piano Chord Extensions – How to Find 9ths, 11ths, 13ths & Altered Tensions (b9, #9, #11, b13)

追加: 2026-06-05

[00:00:00]So, in jazz, chords go much higher than in other styles of music. Most styles just have root, third, and fifth, but in jazz, we keep going up the stack. So, root, third, and fifth, we can go up to a seventh. We can go up to a ninth. We can go up to 11th.

[00:00:17]And we can go up to a 13th, which is A.

[00:00:21]Now, 13 is the highest number you see in jazz because if you went up another third, you'd come back to the root. So, you don't see 15th chords or 17th chords. 13 is the highest number.

[00:00:34]>> [music] >> And the reason that we call this 9, 11, 13 instead of 2, 4, and 6 is it's to reflect the fact that we're building chords. And chords skip every other note. They're built in thirds, so the numbering reflects that. 1, 3, 5, [music] 7, 9, 11, 13. Whereas, if you're talking about a scale, you would say 1, 2, 3, 4, 5, 6, 7 because scales are built in step.

[00:01:03]Now, in jazz, the root, third, fifth, [music] and seventh are what's called chord tones. These are lower down the chord, and these really set the foundation of what chord type it is, whether it's a major seven [music] chord, a minor seven chord, or a dominant seven chord.

[00:01:16]>> [snorts] >> And then the ninth, the 11th, and 13th are called chord extensions, [music] also known as the extended harmony notes.

[00:01:25]Now, you can add chord extensions [music] to any chord as you're playing through a jazz song, whether it's a major seven chord, a minor seven chord, or a dominant seven chord. Now, [music] to find a chord extension, we always build off the major scale. So, if we have a C chord, >> [music] >> regardless of whether it's a major seven chord, minor seven, or dominant seven, the ninth is always going to be based off of the major scale. So, you map out the notes of C major [music] scale.

[00:01:54]Whole step, whole step, then a half step between three and four, and then whole step, whole step.

[00:02:01]So, you only have to find the ninth, 11th, and 13th, and these extensions are always based off the major scale.

[00:02:07]>> [music] >> So, let's say you're on an F chord, and you want to find the ninth, well, you just imagine an F major scale, and you find the ninth that way. If you want the 11th, count up an F major scale, it would be whole step, and then half step.

[00:02:24]And if you want to add the 13th, just run [music] up F major scale, and it's going to be a D. Now, in addition, these chord extensions could be sharpened or flattened. So, over a C7 chord, D [music] is the natural ninth, but we could make it a flat nine, in which case you just move it down a half step.

[00:02:43]>> [music] >> D flat is the flat nine, or you could make it a sharp nine, just sharpen it, D sharp.

[00:02:50]Now, these are called altered extensions when you sharpen or flatten them. Now, there's only four common altered extensions, and these are always found over dominant seven chords. Those are going to be the flat nine, >> [music] >> the sharp nine, the sharp 11, and the flat 13. And the trick to finding any extension is to run up the notes of the major scale first, find the natural extension, and then if you want to alter it, do that next. So, if you want the flat 13, find the natural 13th first, it's A, and then flatten it.

[00:03:23]If you want the sharp 11, find the natural 11th first, major scale, to the fourth, [music] which is the 11th, and then sharpen it.

[00:03:32]And if you want the sharp nine, find the natural nine first by running up the major scale, >> [music] >> and then sharpen it.

[00:03:40]And if you want the flat nine, natural nine [music] first, then flatten it.