This article uses Fretspace  to explore blues scales. These are pentatonic scales that have been extended by adding one or more chromatic notes between the existing notes. Chromatic (in this context)  means that a note is outside the key signature. In the key of C, the white notes on a piano are diatonic (scale) notes and the black notes are chromatic notes.

Minor Blues scale

The most commonly used blues scale is the Minor Blues scale, which is the same as the Minor Pentatonic scale with the addition of a flattened fifth between the fourth and fifth degrees of the Minor Pentatonic scale. Add a standard first-position A Minor Pentatonic shape in Fretspace, and then click in the space between D and E on the fifth string while holding down the Option key. This will convert the A Minor Pentatonic shape into an A Minor Blues shape. Holding down the Option key causes Fretspace to add the same note in other octaves.

The flattened fifth is a characteristic blues note, along with the flattened third and flattened seventh, which we looked at in Pentatonic scales. You can emphasize this note, as well as using it as a passing note between fourth and fifth degree notes. It’s also common to bend a fourth note up to a flattened fifth (semitone bend) or to a normal fifth (two-semitone bend). The flattened fifth forms a tritone with the root of the scale (there are six semitones between the root and a flattened fifth). This is a dissonant interval. Hendrix used it in the introduction to Purple Haze.

You can convert any Minor Pentatonic shape into a Minor Blues shape by adding a flattened fifth. Here are the five basic shapes of the Minor Blues scale. To create these shapes in Fretspace, take the five basic shapes of the Minor Pentatonic scale, turn on Show Degrees, and Option-click between the third and fourth degrees where they are two frets apart.

Major Blues scale

As you might expect, the Minor Blues scale has a major counterpart, which is the Major Blues scale. In Fretspace, you can take a Minor Blues shape and convert it into a Major Blues shape by clicking on the Name popup in the Inspector panel. Here is the C Major Blues equivalent of the first-position A Minor Blues shape.

The notes are the same, but the root is C rather than A. In Fretspace, click on Show Degrees in the Inspector panel, and it will show you the degree values of these notes:

As you can see, Eb is a flattened fifth (b5) in the A Minor Blues scale and a flattened third (b3) in the C Major Blues scale. The flattened third, like the flattened fifth, is a characteristic blues note. Adding flattened thirds to a major scale creates a major blues sound that is characteristic of bluegrass and country music (as well as being found in many other styles of music).

It’s common to bend a second note up to a flattened third (semitone bend) or to a major third (two-semitone bend). These bends are identical to the bends that are used with the Minor Blues scale.

You can convert any Major Pentatonic shape into a Major Blues shape by adding a flattened third. Here are the five basic shapes of the Major Blues scale. To create these shapes in Fretspace, take the five basic shapes of the Major Pentatonic scale, turn on Show Degrees, and Option-click between the second and third degrees where they are two frets apart.

Blues scales with other flattened notes

Although the scales we have looked at are the most commonly known versions of the Minor Blues and Major Blues scales, there are other versions of these scales that contain additional flattened notes. If you look at a standard (major or minor) pentatonic shape, you will see that there are three places where notes are separated by a two-fret interval. Here is a fifth-position major pentatonic shape:

We converted this into a Major Blues shape by Option-clicking between the second and third notes on the fifth string. So what happens if we Option-click between the fifth and sixth degrees on the fourth string, and between the root and second degree on the third string? Try it in Fretspace. Add the previous shape, duplicate it (⌘D) and Option-click between the second and third notes. Duplicate that shape and Option-click between the fifth and sixth notes. Then duplicate that shape and Option-click between the seventh note and the root:

Fretspace labels these shapes Major Blues, Major Blues 2, and Major Blues 3. Major Blues 2 and Major Blues 3 are not standard names: there are no standard names for these scales, and they are not commonly discussed—but they are useful in their own right. Rather than thinking of them as separate scales, it is probably more helpful to think of them as extended versions of the Major Blues scales. Alternatively, all these scales can be regarded as extended versions of the Major Pentatonic scale. Wherever you might play a Major Pentatonic scale, you can extend it by adding a flattened third, flattened sixth, or flattened second.

Flattened notes are commonly used as chromatic grace notes or as passing notes. A chromatic grace note is played briefly before another note that is a semitone higher: for example, you could play a flattened third and hammer on immediately afterwards to create a major third. Ditto with flattened sixths and seconds. A chromatic passing note is a note that is played between two other notes that are two semitones apart. Using hammer-ons, you could play a second note, followed by a flattened third, followed by a major third. Or you could use pull-offs to play a third followed by a flattened third followed by a second. You can also bend between any of these notes: bending a second to a third, or fifth to a sixth (or bending down from a sixth to a fifth, or third to second) are common bends. Bending a root to a second, or bending down from a second to a root also sounds great.

Here are the blues equivalents of diagonal Major Pentatonic shapes:

With these shapes, the flattened third is commonly played by sliding the third finger between the second and third notes, but it can also be played in other ways, using hammer-ons, pull-offs, bends, or separate picking. The other chromatic notes can be played in the same ways.

We can extend other pentatonic scales in the same way—by adding chromatic notes between any notes that are a whole tone (two frets) apart. Here are some minor blues scales. Add a Minor Pentatonic shape in Fretspace, duplicate it (⌘D) and Option-click between the fourth and fifth notes. Duplicate that shape and Option-click between the flattened seventh and root. Then duplicate that shape and Option-click between the flattened third note and the fourth:

As before, it’s more helpful to think of the Minor Blues 2 and Minor Blues 3 scales as extended versions of the Minor Blues scale than to think of them as separate scales. Adding a major third to the Minor Blues scale converts it into a scale that can be used with major chords in non-blues progressions. When it is used in this way, the major third becomes a main note and the minor third becomes a chromatic note, and is used as a grace note or passing note.

Dominant Blues scale

The Dominant Blues scale is the same as a Dominant Pentatonic scale with the addition of a flattened third. Add the five shapes of the Dominant Pentatonic scale in Fretspace, and Option-click to add a flattened third between the second and third notes where they are two frets apart:

You can add other chromatic notes between any two notes that are two frets apart (e.g. b7 and root, or root and second).

You can use a Dominant Blues scales as an alternative to the Dominant Pentatonic scale. The Dominant Blues 2 and Dominant Blues 3 scales may be regarded as extensions of the Dominant Pentatonic and Blues scales rather than as separate scales.

Dorian Blues scale

The Dorian Blues scale is the same as a Dorian Pentatonic scale with the addition of a flattened fifth. Add the five shapes of the Dorian Pentatonic scale in Fretspace, and Option-click to add a flattened fifth between the fourth and fifth notes where they are two frets apart:

You can add other chromatic notes between any two notes that are two frets apart (e.g. fifth and sixth, or b3 and fourth).

Think of these as extensions of the Dorian Pentatonic and Blues shapes, rather than separate scales.

Dorian Pentatonic and Dorian Blues scales can be used as alternatives to the standard Minor Pentatonic and Minor Blues scales. The presence of a sixth note in place of a minor seventh gives them a slightly jazzy sound.

Sus6/9 Blues scale

The Sus6/9 Blues scale is the same as a Sus6/9 Pentatonic scale with the addition of a flattened fifth. Add the five shapes of the Sus6/9 Pentatonic scale in Fretspace, and Option-click to add a flattened fifth between the fourth and fifth notes where they are two frets apart:

You can add other chromatic notes between any two notes that are two frets apart (e.g. fifth and sixth, or root and second). Think of these as extensions of the Sus6/9 Pentatonic and Blues shapes, rather than separate scales.

The top part of a third-position Sus6/9 Blues shape resembles the blues box that B. B. King used and popularized.

This shape is useful for blues solos, because it contains notes that are not in the standard Minor Blues scale and which add color to that scale: specifically the second (or ninth) note (B in this case) and the sixth note (F# in this case). In addition, these two notes can also be bent by a semitone to add two notes from the standard Minor Blues scale: bending B to C in this case gives us a minor third, and bending F# to G gives us a minor seventh. Bending also gives us other notes: the second note (B) can be bent by two semitones to add a major third (C#) or by three semitones for a fourth (D), and the sixth note (F#) can be bent by two semitones to add a major seventh (G#), which you might use over an E chord. The minor third and minor seventh of the standard Minor Blues scale can also be added as fretted notes:

You can also play this shape at other positions. Here it is (without added notes from the Minor Blues scale) at the 14th fret:

B. B. King used notes from the blues box and combined them with skilled use of finger vibrato to achieve a sweet singing sound in his solos.

Reference charts

Let’s add blues scales to our collection of reference charts. Open the Guitar Scales document that you should already have—if you don’t, go back and create it, following steps in the Pentatonic Scales article.

Major Blues chart

Select the first (Major Pentatonic) chart in the Guitar Scales document. Click on it in the Charts area to the left of the main window area and drag it to the bottom of the list while holding down the Option key. This will create a copy of the Major Pentatonic chart. Rename this copy to Major Blues.

Major Blues shapes

Click on the first C Major Pentatonic shape (to select it), hold down the Option key, and click to add a flattened third (b3) note. The easiest way to do this is to click between the dots labelled “2” and “3” where they occur on the same string, but you can click after any “2” dot or before any “3” dot. Option-clicking adds a dot where you click and at matching places within the scale, converting it into a Major Blues scale.

Option-click to add a flattened third to each of the other Major Pentatonic shapes and convert them into Minor Blues shapes.

Minor Blues shapes

Option-click to add a flattened fifth (b5) note to each of the A Minor Pentatonic shapes and convert them into Minor Blues shapes.

Sus6/9 Blues shapes

Option-click to add a flattened fifth (b5) note to each of the G Sus6/9 Pentatonic shapes and convert them into Sus6/9 Blues shapes.

Dominant Blues chart

Click on the Dominant Pentatonic in the Charts area on the left of window and drag it to the bottom of the list while holding down the Option key. This will create a copy of this chart. Rename this copy to Dominant Blues.

Dominant Blues shapes

Option-click to add a flattened third to each of the Dominant Pentatonic shapes and convert them into Dominant Blues shapes.

Dorian Blues shapes

Option-click to add a flattened fifth to each of the Dorian Pentatonic shapes and convert them into Dorian Blues shapes.

Diagonal Blues chart

Click on the Diagonal Pentatonic Shapes chart in the Charts area on the left of window and drag it to the bottom of the list while holding down the Option key. This will create a copy of this chart. Rename this copy to Diagonal Blues Shapes.

Diagonal Blues shapes

Option-click to add a flattened third to each of the diagonal Major Pentatonic shapes and convert them into Major Blues shapes. Do the same with the diagonal Dominant Pentatonic shapes.