What Are Altered Chords?
A plain dominant 7th chord pulls toward the tonic. An altered dominant yanks toward it. By raising or lowering the fifth and ninth, you stack dissonance that the ear urgently needs to resolve — and when resolution comes, it lands harder than any unaltered V–I ever could. Four alterations. One scale that contains all of them. This is the harmonic engine of jazz.
What is an altered chord?
An altered chord is a dominant 7th chord with one or more of its notes chromatically raised or lowered. The alterations always land on the fifth or the ninth — never the root, third, or flat seventh, because those three notes define the chord as a dominant 7th. Alter them and it stops being a dominant chord entirely.
The formula: start with a dominant 7th (1 – 3 – 5 – ♭7) and apply any combination of the four available alterations:
- ♭9 — lower the ninth by a half step
- ♯9 — raise the ninth by a half step
- ♭5 — lower the fifth by a half step (also called ♯11)
- ♯5 — raise the fifth by a half step (also called ♭13)
Every complex altered chord symbol you’ll find on a jazz lead sheet — G7♭9♯5, C7♯9♯11, F♯7alt — is a combination of these four. The vocabulary is finite.
Altered chords almost always live on the V chord of a progression — the chord that’s about to resolve to the tonic. A plain V7 already contains a tritone that wants to resolve. Alterations add more dissonance on top, which makes the resolution land harder when it arrives.
The four alterations
Each alteration produces a distinct sound. They can be combined — but each has its own character worth learning separately before stacking them.
| Alteration | Notes in G7 | What changes | Sound character |
|---|---|---|---|
| ♭9 | G – B – D – F – A♭ | 9th lowered ½ step | Most dissonant — half-step above root, classical/jazz standard |
| ♯9 | G – B – D – F – A♯ | 9th raised ½ step | The Hendrix chord — major 3rd clashes with ♯9 (= minor 3rd) |
| ♭5 (= ♯11) | G – B – D♭ – F | 5th lowered ½ step | Whole-tone flavor — tritone symmetry, floating and ambiguous |
| ♯5 (= ♭13) | G – B – D♯ – F | 5th raised ½ step | Altered-scale tension — implies the G altered / A♭ melodic minor |
2.1 ♭9 — the classical one
Notes in G7♭9: G – B – D – F – A♭ · Page: 7♭9 chords →
The flat nine is the most common and most historically established alteration. The A♭ sits a half step above the root G, creating a minor-ninth interval — one of the sharpest dissonances in Western harmony. Classical composers used it for dramatic effect; jazz adopted it as essential vocabulary.
Famous contexts:
- Schubert’s “Erlkönig” — the opening piano figure is built on ♭9 harmony
- Minor-key ii-V-i progressions — the G7♭9 resolving to Cm is the definitive sound
- Broadway and film scores — wherever dramatic cadences appear
When to use it: On the V chord resolving to a minor tonic. When you want the sharpest possible resolution tension without going fully “outside.”
2.2 ♯9 — the Hendrix chord
Notes in G7♯9: G – B – D – F – A♯ · Page: 7♯9 chords →
The sharp nine contains a collision that shouldn’t work but absolutely does: a major third (B in G7♯9) and a sharp nine (A♯, which is enharmonically the same as B♭ — a minor third). Major and minor stacked together on the same root. The result is simultaneously bluesy, edgy, and unstable.
Famous contexts:
- Jimi Hendrix — “Purple Haze” opens on E7♯9
- Stevie Wonder — uses ♯9 chords throughout his catalog
- Hard bop and post-bop jazz — where blues and jazz harmony overlap
When to use it: For that particular major-minor ambiguity. When you want a chord that feels both inside and outside simultaneously — blues on top of jazz.
2.3 ♭5 / ♯11 — the whole-tone one
Notes in G7♭5: G – B – D♭ – F · Pages: 7♭5 · 7♯11
The same note, two names. ♭5: the natural fifth is lowered, replacing it with a tritone above the root. ♯11: the natural fifth stays, and a raised eleventh is added above it. Which label you use depends on whether the voicing includes the natural fifth or not.
The ♭5 creates a whole-tone-scale flavor — floating, unmoored, symmetrical. Because G7♭5 contains the tritone G–D♭, which is enharmonically the same as C♯–G, this chord easily implies a tritone substitution. The chord can resolve in two directions equally well.
When to use it: When you want a whole-tone or impressionist texture. In tritone-substitution contexts where the chord needs to imply two different tonal centers.
2.4 ♯5 / ♭13 — the altered-scale one
Notes in G7♯5: G – B – D♯ – F · Pages: 7♯5 · 7♭13
Again, two names for the same note. ♯5: the natural fifth is raised, replacing it. ♭13: the natural fifth stays, and a lowered thirteenth is added above. The ♯5 version strongly implies the altered scale; the ♭13 version can imply the half-whole diminished scale depending on context.
The sharp-five alteration is less aggressive than the flat-nine but still unmistakably outside. It’s the sound of modern jazz comping — not the dramatic ♭9, but an angular, harmonically rich texture that signals “this is a sophisticated dominant chord.”
When to use it: In modern jazz contexts where you want altered tension without the overt drama of the flat nine. As part of a full 7alt voicing with multiple alterations stacked.
The 7alt chord: when the chart just says “alt”
On jazz lead sheets, you’ll sometimes see a chord written as G7alt with no specific alterations listed. Just “alt.”
This is shorthand: the composer is telling you to play some combination of ♭9, ♯9, ♭5, and ♯5. The specific choice is left to your taste. Most jazz pianists interpret 7alt as permission to use any or all four alterations, drawing notes from the altered scale.
The most-used G7alt voicing contains four notes — the guide tones plus two alterations:
G7alt voicing A: B – F – A♭ – E♭
3rd: B · ♭7: F · ♭9: A♭ · ♭13 (♯5): E♭
G7alt voicing B: F – B – E♭ – A♭
♭7: F · 3rd: B · ♭13: E♭ · ♭9: A♭ (same notes, different order)
Both voicings contain the same four pitches. Which you use depends on voice leading — which arrangement connects most smoothly to the chord before it and after it.
When G7alt resolves to Cmaj7, four different voices can move by half step simultaneously. That density of resolution is what makes altered dominants sound so powerful compared to plain V7 chords.
The altered scale — one shortcut for everything
Every altered dominant chord has a matching scale you can improvise over: the altered scale, also called Super Locrian. It’s the seventh mode of the melodic minor scale, and it contains all four possible alterations simultaneously.
| Degree | 1 | ♭9 | ♯9 | 3 | ♯11 | ♭13 | ♭7 |
|---|---|---|---|---|---|---|---|
| G altered | G | A♭ | A♯ | B | C♯ | E♭ | F |
The degrees in red — ♭9, ♯9, ♯11, ♭13 — are all four alterations, collected in one scale. The chord tones (1, 3, ♭7) anchor the scale to the dominant function. The altered scale is the chord spelled out linearly.
The shortcut
To find the altered scale for any dominant chord: play the melodic minor scale that starts one half step above the root.
- G7alt → A♭ melodic minor starting on G
- C7alt → D♭ melodic minor starting on C
- F♯7alt → G melodic minor starting on F♯
If you know your melodic minor scales, you already know every altered scale — the notes are the same, just starting from a different position. This is the single most useful shortcut in altered harmony.
Tritone substitution — the other face of altered harmony
Here is one of the most elegant relationships in jazz harmony: the 7alt chord and the dominant 7th chord a tritone away share the same guide tones.
G7 has a 3rd of B and a ♭7 of F. D♭7 has a 3rd of F and a ♭7 of C♭ (= B enharmonically). The guide tones trade roles, but the notes are identical. Both chords contain the same tritone — B and F — and both resolve convincingly to Cmaj7.
This substitution is called tritone substitution. In a ii-V-I in C major:
- Standard: Dm7 → G7 → Cmaj7
- Tritone sub: Dm7 → D♭7 → Cmaj7
The D♭7 creates a half-step descending bass line (D → D♭ → C) that sounds more sophisticated than the root-movement jump of the standard version. Jazz arrangers use this constantly.
The connection to altered chords: G7alt already contains most of the notes of D♭7. The two concepts — altering a dominant and substituting it with a tritone-away dominant — are two sides of the same coin. If you can hear one, you can hear the other.
How to voice altered chords on piano
Altered chords are rarely played with all notes present — too many notes create harmonic mud. The practical approach: keep the guide tones (3rd and ♭7), add one or two alterations, and omit the root when a bassist is covering it.
Minor ii-V-i with altered voicings in C minor
| Chord | Voicing | Notes spelled out |
|---|---|---|
| Dm7♭5 | F – C – E♭ – A | ♭3, ♭7, ♭9, 5 (rootless) |
| G7alt | F – B – E♭ – A♭ | ♭7, 3, ♭13, ♭9 (rootless) |
| Cm7 | E♭ – B♭ – D – G | ♭3, ♭7, 9, 5 (rootless) |
Each chord voice-leads smoothly to the next. Notes move by step. This is why properly voiced altered dominants never feel jarring — the alterations create tension, but the voice leading makes that tension feel inevitable rather than random.
The two-voicing foundation
Learn these two G7alt shapes and transpose to all 12 keys. They cover roughly half of modern jazz comping:
- Voicing A (built from the 3rd): B – F – A♭ – E♭ → resolves to Cmaj7 voicing E – G – B – D
- Voicing B (built from the ♭7): F – B – E♭ – A♭ → resolves to Cmaj7 voicing G – B – D – E
Both voicings are the same four pitches in different order. Voice-leading determines which one you play: choose whichever connects most smoothly to the preceding chord.
Five exercises to internalize altered chords
1. The alteration menu: On C7, play each alteration in isolation: C7 plain, then C7♭9, then C7♯9, then C7♭5, then C7♯5. Listen to each sound separately. Then move around the Circle of Fifths. A week of this makes the four alteration sounds instantly recognizable.
2. The 7alt voicing drill: Learn both rootless G7alt voicings (B–F–A♭–E♭ and F–B–E♭–A♭). Then transpose to all 12 keys — 24 voicings total. When you can play any of them from memory in under two seconds, you're ready to comp through jazz standards.
3. Minor ii-V-i in all keys: In C minor: Dm7♭5 → G7alt → Cm7. Move up a half step: E♭m7♭5 → A♭7alt → D♭m7. Continue around the Circle of Fourths. This is the single most common context for altered dominants in jazz.
4. Melodic minor as altered scale: Pick any dominant chord — say G7. Play A♭ melodic minor starting on G. Identify each altered degree as you play: ♭9, ♯9, ♯11, ♭13. Your ear learns the scale as a chord and the chord as a scale. Do this in all 12 keys.
5. Tritone substitution A/B: Play Dm7 → G7 → Cmaj7. Then play Dm7 → D♭7 → Cmaj7. Then try Dm7 → D♭7♯11 → Cmaj7. Each version resolves differently. Training your ear to hear these distinctions is how you start composing with altered harmony instead of just memorizing voicings.
Common mistakes
Mistake: Altering non-dominant chords.
Alterations belong on V chords that are about to resolve to a I chord. Loading a Cmaj7 with a ♭9 doesn't heighten resolution — it just sounds wrong, because there's no resolution coming. Alter V chords. Leave I and IV chords alone.
Mistake: Stacking every alteration at once.
Playing all four alterations simultaneously produces harmonic mud. Most jazz pianists use one or two alterations per chord. "Less is more" applies hard to altered harmony — the art is in which alteration you choose, not how many you pile on.
Mistake: Forgetting to resolve the tension.
Altered chords are tension-builders. If you play a G7alt and don't resolve to C (or a close substitute), the ear feels cheated. Altered chords without resolution are half-told jokes. The tension only pays off when it releases.
Mistake: Confusing altered and diminished.
Both use ♭5. Both sound tense. But a G7♭5 is still a dominant chord (contains a major 3rd); a G°7 is fully diminished (contains a minor 3rd). They resolve to different places. If you're hearing the major third, it's altered. If the third is minor, it's diminished.
Mistake: Playing altered notes as passing tones.
In improvisation, altered notes must be emphasized — played on strong beats, held long enough for the ear to register them. If you bury the ♭9 as a quick passing tone between chord tones, the alteration gets lost. Sit on the altered note. Let it breathe.
Explore every altered chord type
Related theory
Frequently asked questions
What is an altered chord?+
An altered chord is a dominant 7th chord with one or more of its notes chromatically raised or lowered. The alterations happen on the 5th or the 9th — producing ♭9, ♯9, ♭5, and ♯5 variants. Altered chords create maximum tension on V chords that resolve to a tonic.
What does 7alt mean on a lead sheet?+
7alt is shorthand for "altered dominant." The composer is telling you to play some combination of ♭9, ♯9, ♭5, and ♯5. The specific choice is left to your taste. Most pianists interpret 7alt as permission to draw notes from the altered scale, which contains all four alterations simultaneously.
What is the difference between ♭5 and ♯11?+
They are the same note called different names depending on context. If the chord drops the natural 5 and replaces it, call it ♭5. If the chord keeps the natural 5 and adds a raised 11 above, call it ♯11. The sound is similar; the voicing differs.
What is the altered scale?+
The altered scale is the 7th mode of the melodic minor scale. It contains every altered tension — ♭9, ♯9, ♭5 (♯11), ♭13 (♯5) — plus the essential chord tones (1, 3, ♭7). It is the go-to scale for improvising over any dominant 7 with alterations.
How do I find the altered scale for a dominant chord?+
Play the melodic minor scale that starts one half step above the root of the dominant chord. For G7alt, play A♭ melodic minor starting on G. For C7alt, play D♭ melodic minor starting on C. This works in all 12 keys.
What is tritone substitution?+
Tritone substitution replaces a dominant 7 chord with another dominant 7 chord a tritone (three whole steps) away. For G7, the tritone sub is D♭7. Both chords share the same guide tones and resolve to the same tonic. Tritone subs are closely related to altered dominants — they contain many of the same notes.
Can altered chords be used in pop or rock?+
Yes, but sparingly. The 7♯9 appears in "Purple Haze" and throughout R&B. Using altered chords in pop means placing them on V chords just before a chorus or bridge, where the extra tension creates a satisfying payoff on resolution.
Which alteration should I learn first?+
The ♭9. It is the most common in classical and jazz, and it is the alteration that most immediately teaches your ear what altered tension sounds like. Start with G7♭9 → Cmaj7, then G7♭9 → Cm7. Learn that sound in all 12 keys, then add the other three alterations one at a time.
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