Music 101: What Is a Musical Scale? Plus: Learn the Difference Between Major Scale vs. Minor Scale

A scale is a sequence of notes chosen from the 12 available pitches. (Certain musical traditions, particularly those of South Asia, include microtonalities that expand the number of available pitches.)

There is no rule stating how many notes a scale must include. The most common scales in Western music contain seven pitches and are thus called “heptatonic” (meaning “seven tones”). Other scales have fewer notes—five-note “pentatonic” scales are quite common in popular music. There’s even a scale that uses all 12 pitches: it’s called the “chromatic” scale.

Western music contains a wide array of scales, although some are more commonly utilized than others. The building block of Western music is the major scale, which consists of seven notes. Starting from the lowest note, and going up, they are:

1—the “root” of the scale
2—a whole step up from the root
3—a whole step up from the 2nd
4—a half step up from the 3rd
5—a whole step up from the 4th
6—a whole step up from the 5th
7—a whole step up from the 6th

Then, with one more half step, arrive back to the “root”—only now an octave higher than before.

The key note in the major scale is the 3rd degree. It’s what gives the scale its “major” sound—one that is happy and uplifting rather than dark and ominous. Another key note is the 7th degree, which is sometimes called the “leading tone” because it “leads” you right back into the root of the scale.

The second most fundamental building block of western music is the minor scale, which most people consider to sound darker and sadder (sometimes even scarier) than the major scale. There are actually three minor scales—natural minor, harmonic minor, and melodic minor—but it’s the natural minor scale that will sound most familiar to Western ears. It is similar to a major scale, but with a few half steps where there were previously whole steps.

1—the “root” of the scale
2—a whole step up from the root
b3—a half step up from the 2nd
4—a whole step up from the 3rd
5—a whole step up from the 4th
b6—a half step up from the 5th
b7—a whole step up from the 6th

And then one final whole step to get back to the root—but again it’s an octave higher than before.

In the harmonic minor scale, the 7th scale degree is raised. We would say that while a natural minor scale has a “flat seventh” or “minor seventh,” the harmonic minor scale has a “natural seventh.” Yes, you read that correctly—that natural seventh isn’t in the natural minor scale! Let’s compare the two scales to see the difference.

The E natural minor scale consists of 7 notes: E - F# - G - A - B - C - D
The E harmonic minor scale also consists of 7 notes: E - F# - G - A - B - C - D#

The only difference between the two is that the D has been raised to D#. This makes that 7th degree a leading tone, just like you’d have in a major scale. The harmonic minor scale produces an “Arabian” sound, as it is the preferred minor scale in the musical traditions of North Africa and the Iberian peninsula. (But it’s also used in rock music: check out Slash’s solo in the Guns N’ Roses hit “Sweet Child O’ Mine” to hear a mixture of blues and harmonic minor.)

The melodic minor scale is an odd one. When going up the scale, it’s played with a flat third (or minor third) degree, but all the other notes are the same as a major scale (including a natural 6th and natural 7th degree). But going down the melodic minor scale, you play it just like a natural minor scale. To demonstrate:

The E melodic minor scale going up: E - F# - G - A - B - C# - D#
The E melodic minor scale going down: E - D - C - B - A - G - F#

Of these three minor scales, the melodic minor scale is least frequently used. You’ll find it in some classical music, and some jazz musicians will interpolate it into their solos.

Pentatonic scales are reduced versions of major and minor scales.

A major pentatonic scale is a major scale without the 4th and 7th scale degrees. This leaves us with the following scale degrees:

1 - 2 - 3 - 5 - 6

The minor pentatonic scale is a variation on the natural minor scale. To turn a natural minor scale into a minor pentatonic scale, eliminate the 2nd and 6th scale degrees. This leaves us with:

1 - b3 - 4 - 5 - b7

Blues scales are pentatonic scales with added notes, and those notes vary from player to player. To “blues up” a major pentatonic scale, consider adding:

• A flat fifth (for instance Ab in the key of D major)
• A flat third (to go along with the natural third, for instance, F in the key of D major)
• A flat seventh (for instance C in the key of D major)
• The natural 7th (which would be C# in the key of D major), but only as a “passing tone” between C and D. Don’t linger on the natural 7th if you want to sound bluesy
• In reality, you can make any note work in the major blues scale if you don’t linger on it too long. But one note to generally avoid is the flat 6th (for instance Bb in the key of D major). This note will really fight the major tonality

To “blues up” a minor pentatonic scale, consider adding:

• A flat 5th
• A natural 7th in addition to the flat 7th that’s already in the minor pentatonic scale. (But only use it in passing between the flat 7th and the root—so in the G minor blues scale, you can use an F#, but only to connect an F to a G.)
• You can add pretty much any note to the minor pentatonic scale except the natural 3rd. Within the G minor blues scale, this means you should not play a B natural. It will completely clash with the minor character of everything else you’re playing.
• But other than that natural 3rd, pretty much any note can work right if you know what you’re doing. It takes practice and trial-and-error, but you’ll be able to find which notes are the best ones to add on to a pentatonic scale.

Modes are derived from the notes of a major or minor scale. With the exception of a few highly ambitious jazz players, most musicians use modes derived from the major scale. These modes are as follows:

• Ionian Mode. A major scale pattern starting on the root. Therefore a C major scale and the C Ionian mode have the same exact set of notes: C-D-E-F-G-A-B. This means that “Ionian mode” is just a fancy way of saying “major scale.”
• Dorian Mode. A major scale pattern starting on the 2nd degree. The Dorian mode is a cousin to the minor scale and is quite popular with guitarists—from jazz greats like Pat Martino to shredders like Kirk Hammett.
• Phrygian Mode. A major scale pattern starting on the 3rd degree. The Phrygian mode also has a minor tonality and tends to evoke the Arabian music of Spain and North Africa.
• Lydian Mode. A major scale pattern starting on the 4th degree. The Lydian mode is closely related to a major scale and tends to evoke a “lifting” sensation. It’s popular in inspirational film music like John Williams’ score for ET: The Extra-Terrestrial.
• Mixolydian Mode. A major scale pattern starting on the 5th degree. Also closely related to a major scale, the Mixolydian mode is heard all over rock, blues, and fusion. Listen to the guitar solos in Steely Dan’s “Reelin’ In The Years” for some fantastic Mixolydian playing.
• Aeolian Mode. A major scale pattern starting on the 6th degree. This is actually the same exact note pattern as a minor scale, so like the Ionian mode, saying “Aeolian mode” is just a fancy way to say “minor.”
• Locrian Mode. A major scale pattern starting on the 7th degree. The Locrian mode is dense and thorny and rarely used. Sometimes jazz soloists use it over diminished chords, but it doesn’t sound pleasing in long passages.

Learn more about musical modes here.