HearmonyThe Blues Scale: Notes, Formula and Why Blue Notes Sound Blue
The blues scale is the minor pentatonic scale with one extra note, the flatted fifth. Its formula is 1, ♭3, 4, ♭5, 5, ♭7, so the A blues scale is A C D E♭ E G. That added ♭5, together with the ♭3 and ♭7 played against major-sounding chords, gives the scale its gritty, bent "blue" sound.
There is also a major blues scale (1, 2, ♭3, 3, 5, 6), which sounds sweeter. This guide spells both in the keys guitarists and pianists use most, explains what a blue note actually is, and gives you a way to hear the effect instead of just playing the shape.
What is the blues scale?
The blues scale, often called the minor blues scale, is a six-note scale: the five notes of the minor pentatonic scale plus a ♭5 squeezed between the 4th and 5th. In A, the minor pentatonic is A C D E G, and adding E♭ gives A C D E♭ E G.
Counted in semitones, the steps are 3, 2, 1, 1, 3, 2. Those two half steps in a row (D to E♭ to E) are the only chromatic spot in the scale, and they are where most blues licks slide, bend and hammer on.
Blues scale notes in every common key
The ♭5 is the note people most often get wrong when spelling the scale. It is always six semitones above the root. This table gives the minor blues scale in the keys you meet most in blues and rock.
| Key | 1 | ♭3 | 4 | ♭5 | 5 | ♭7 |
|---|---|---|---|---|---|---|
| A | A | C | D | E♭ | E | G |
| E | E | G | A | B♭ | B | D |
| C | C | E♭ | F | G♭ | G | B♭ |
| G | G | B♭ | C | D♭ | D | F |
| D | D | F | G | A♭ | A | C |
In real music the same key is often spelled as a sharpened 4th when the line climbs (D, D♯, E in A) and as a flatted 5th when it falls (E, E♭, D). Both names point to the same pitch; theory books use ♭5 in the formula.
What is the major blues scale?
The major blues scale is the major pentatonic plus a ♭3: 1, 2, ♭3, 3, 5, 6. Its signature move is the ♭3 sliding up into the major 3rd, a half-step "smear" you hear constantly in country, boogie-woogie and jump blues.
| Key | Major blues scale | Same notes as |
|---|---|---|
| C | C D E♭ E G A | A minor blues |
| A | A B C C♯ E F♯ | F♯ minor blues |
| E | E F♯ G G♯ B C♯ | C♯ minor blues |
| G | G A B♭ B D E | E minor blues |
As with the pentatonic scales, each major blues scale contains the same six notes as the minor blues scale a minor third lower. The difference is which note you treat as home. Over an A7 chord, the A minor blues sounds tough and edgy; the A major blues sounds brighter and more playful. Many players switch between them inside one solo.
What are blue notes, and why do they sound blue?
Blue notes are the ♭3, ♭5 and ♭7 of the key, sung or played with an expressive bend. They sound blue because they clash with the chords underneath, which in blues are usually major or dominant 7th chords, not minor ones.
Take a blues in A. The home chord is A7, spelled A C♯ E G, with a major third (C♯). When the melody plays C, the ♭3, against that C♯, you hear a minor note over a major chord. That rub is the core of the blues sound. Singers and guitarists often don't land squarely on C or C♯ but bend somewhere between them, a pitch a piano cannot play. Pianists imitate it by crushing the two notes together, playing C quickly into C♯.
| Blue note | In A | Against the A7 chord (A C♯ E G) | Effect |
|---|---|---|---|
| ♭3 | C | a half step below the chord's C♯ | the minor-over-major rub, often bent up |
| ♭5 | E♭ | a tritone above the root, a half step below E | sharp tension, best used in passing |
| ♭7 | G | the chord's own 7th | fits the chord, adds the dominant color |
The ♭7 explains why blues harmony is built on dominant 7th chords: the scale's ♭7 is already part of the chord, so it sounds at home. The guide to dominant, major and minor 7th chords shows how that chord is built. For the history of the term, the Wikipedia entry on blue notes is a good starting point.
How do you play the blues scale on guitar?
On guitar, the easiest A blues scale shape is the A minor pentatonic box at the 5th fret with the ♭5 (E♭) added. Two extra frets turn the familiar box into the blues scale:
- 5th string, 6th fret: E♭, between D (5th fret) and E (7th fret).
- 3rd string, 8th fret: E♭ again, one octave up, after C (5th fret) and D (7th fret).
The run on the 5th string, frets 5, 6 and 7 (D, E♭, E), is the classic blues-scale move. Move the whole shape so the 6th-string root lands on E (12th fret) for the E blues scale, or on G (3rd fret) for G. On piano, try the A blues scale in the right hand over a left-hand A7, and play the ♭5 as a quick passing note rather than a note to rest on.
How to hear the blues scale and use it well
You hear the blues scale best against a major or dominant chord, because the blue notes only sound blue when something rubs against them. These five steps take about five minutes.
- Hear the rub. Hold A7 (A C♯ E G) and play C over it, then C♯. The first sounds bluesy and tense, the second sounds settled.
- Hear the ♭5 in passing. Play D, E♭, E slowly, then quickly. Slow, the E♭ sounds wrong; quick, it sounds like the blues.
- Compare with the pentatonic. Play a short phrase using only A C D E G, then repeat it with E♭ added before the E.
- Switch to major blues. Over the same A7, play A B C C♯ E F♯, sliding C into C♯. Notice how much brighter it is.
- Land on chord tones. End each phrase on A, E or G, and let the C and E♭ be on the way there.
Common mistakes
- Sitting on the ♭5. Held over the I chord, E♭ against A sounds like a mistake. Use it as a step between D and E.
- Ignoring the chord changes. The scale works over all three chords of a blues in A (A7, D7, E7), but each note's job changes: G is the chord's own 7th over A7 and a bluesy ♭3 over E7 (E G♯ B D), while C♯ from the major blues scale clashes with the D7's C natural. Listen as the chords move.
- Calling the ♭3 a "wrong note". Over a dominant 7th chord, the minor third is the point. Bend it, slide it, but keep it.
Self-test: name the scale. G B♭ C D♭ D F · C D E♭ E G A · E G A B♭ B D · A C D E G. Answers: G blues scale; C major blues scale; E blues scale; A minor pentatonic (no ♭5, so not the blues scale).
Most blues-scale playing happens over one chord pattern, the twelve-bar form. The guide to the 12-bar blues progression shows which chord sits under each bar, so you know when C♯ fits and when it doesn't.
Train the blues sound in Hearmony
Hearmony doesn't teach scales on an instrument, but it trains the sounds the blues scale is built from. Chord Garden starts with major versus minor chords, the same major-third versus minor-third contrast as the blue ♭3. Interval Peaks has a unit on the tritone, the distance from the root to the ♭5, and its Summit mix covers every interval up to the octave in both directions. Seventh Heaven opens with the dominant 7th, which the app itself calls "the bluesy chord", and asks you to tell C7 apart from plain major and minor.
Short daily rounds of those three skills sit well next to the guitar or piano exercises above, and the beginner ear training plan shows the order to take them in. Hearmony is an iPhone app; you can find it on the App Store.