What Scale Should I Play?

Figuring out what scale to use when playing over chord changes doesn't have to be hard. This three-page lesson lays out a set of rules of thumb that work for most songs — how to read the key and feel of a progression, when the pentatonic scales are all you need, and how to recognize the situations that call for something more.

Download the PDF above to work through the examples.

What scale should I play?

One of the most common questions beginner improvisers ask is: “What scale should I play over that chord progression?” While there is often no single right answer, there are some rules of thumb that can help in most situations. In this lesson, I’ll share a few that will empower you to find the right answer for most songs.

This discussion relies on a basic understanding of the major scale modes, so it may be helpful to watch my video on the modes before proceeding.

Many chord progressions are diatonic, meaning that all of the chords are derived from a single scale (usually one of the major scale modes). To derive a chord from a scale, you start on one of the scale tones and move upward, including every second note, until you’ve collected enough notes to make the type of chord you want. Triads have three notes, and 7th chords have four.

If we represent the major scale as a repeating cycle of notes named by their scale degree, we’d have:

1 - 2 - 3 - 4 - 5 - 6 - 7 - 1 - 2 -3 - 4 - 5 - 6 …

Starting on the first degree and building a triad (a three-note chord), we would have 1 - 3 - 5. If we had started on the 4th scale degree, we would have 4 - 6 - 1. If we were building 7th chords (four-note chords) and started on the 5th scale degree, we would get 5 - 7 - 2 - 4. We call this stacking thirds, and we’ll see why in just a moment.

The major scale consists of whole-step (2-semitone) and half-step intervals in the repeating sequence w - w - h - w - w - w - h. A major third is a 4-semitone distance (which we get when there are two whole steps in a row), and a minor third is a 3-semitone distance (equivalent to a whole-step plus a half-step interval). As a result, in all chords built in this way, the intervals between pairs of adjacent notes are either major or minor thirds.

If we build a triad from the 1st, 4th, or 5th scale degree, we get a major third followed by a minor third, giving us a major triad. If we build from the 2nd, 3rd, or 6th scale degree, we get a minor triad (a minor followed by a major third). A triad built from the 7th scale degree consists of two stacked minor thirds and is called a diminished triad.

Triads built from the major scale (and its modes) have a characteristic sequence of major, minor, and diminished qualities and whole- and half-tone spacing.

The secret to identifying the correct scale to play over a chord progression is recognizing a handful of signature relationships between these chords.

Clue 1: Two minor triads separated by a whole step are almost always the ii and iii chords of the underlying major scale. Similarly, two major triads separated by a whole step are usually the IV and V.

If you see two minor (or two major) triads separated by a whole-step, that tells you instantly which major scale the chord progression is based on.

Clue 2: If two major triads are related by a 4th or 5th, one of them is the I chord.

If there are seventh chords in the progression, that can also provide valuable clues.

Seventh chords built from the major scale.

Clue 3: A dominant 7 chord is almost always the V7 of the underlying major scale. A maj7 chord is either the Imaj7 or IVmaj7.

We can usually identify the underlying major scale using a combination of these three clues, but that doesn’t tell the whole story. We still need to know which mode is being used. To determine the mode, we must know which chord in the progression sounds like home. Home, in this sense, is where the progression feels most at rest. This will often be the very first or last chord in the progression, and it is also often the note played most prominently in the bass line. You’ll probably have to use your ears to figure it out (it’s usually not hard to do). Once we know which root is home, we can map the scale degree of that chord to the appropriate mode: I = Ionian (major scale), ii = Dorian, iii = Phrygian, IV = Lydian, V = Mixolydian, vi = Aeolian (natural minor), and vii = Locrian.

Let’s try this on some examples.

Example 1: The “Stairway to Heaven” outro is often played as Am - G - F. G and F are major triads separated by a whole step, so F is the IV and G is the V of the underlying chord progression, making Am the vi. Since Am sounds like “home,” the underlying scale is the A Aeolian mode.

Example 2: The first few chords of “Little Wing” are Em - G - Am - Em - Bm, and Em sounds like “home.” Am and Bm are minor triads separated by a whole step, so they are the ii and iii of the underlying G major scale. Since this makes Em the vi, the song is in E Aeolian. [Note that there is an F triad later in the chord progression, which does not fit the key (i.e., it is non-diatonic). If you want to go down a music theory rabbit hole, google “Neapolitan chord”.]

Example 3: In the second solo section of “Comfortably Numb,” the chord progression is Bm - A - G - Em - Bm. A and G are major triads separated by a whole step, so they are the IV and V of the underlying D major scale. But since Bm feels like “home” and it’s the vi of D major, the progression is in B Aeolian.

Example 4: Your band is playing over a C/A - D/A vamp. C and D are major triads separated by a whole step, so the underlying scale is G major. Since the bass makes A feel like home, and A is the second scale degree of G major, this is an A Dorian jam. [Incidentally, here’s the easiest way to create a modal feel: play two major chords separated by a whole step over the bass note corresponding to your desired mode. C/E - D/E would be an E Aeolian jam. C - D/C is C Lydian. C/D - D is D Mixolydian. C/G - E/G is G Dorian. Etc.]

Once you have determined the appropriate mode, you still have a choice to make. You can play that mode or stick to a pentatonic scale (or mix the two!). The minor pentatonic will sound great over a minor modal progression (Dorian, Phrygian, or Aeolian). The major pentatonic scale is a solid choice for the major modes (Ionian, Lydian, or Mixolydian), but you can also get a bluesy sound by choosing the minor pentatonic scale in those situations (just remember to bend the minor third a little bit).

Going back to our examples, Am pentatonic was Jimmy Page’s choice for “Stairway to Heaven,” Jimi Hendrix chose Em pentatonic for the beginning of his “Little Wing” solo, and David Gilmour leaned heavily on Bm pentatonic for “Comfortably Numb.” For the A Dorian jam, Am pentatonic is a fine starting point.

Of course, you can also use the full modes. By adding an F note to the Am pentatonic scale, Page hinted at Aeolian. By adding a C note to the Em pentatonic scale, Hendrix hinted at E Aeolian.

This strategy for choosing a scale is not comprehensive, but it will give you a solid starting point for jamming over most chord progressions.

Happy improvising!