When musicians talk about a key, they are referring to a set of notes that all fit together as a musical scale. Music composed in a major key centers around notes from a major scale, while minor key music centers around notes from a minor scale. Every major scale shares a set of notes with a particular minor scale, and every minor scale shares a set of notes with a particular major scale. These pairs share the same key signature and are known as relative keys.

## What Are Relative Keys?

Relative keys are pairs of major and minor musical keys that share the same set of notes. When these notes are played in a certain order, they can “happy” (major key); when the same keys are played in the relative order, they sound “sad” (minor).

## Example of Relative Keys: C Major & A Minor

For instance, the key of C major shares the same notes as the key of A minor, which makes them a pair of relative keys.

Both the C major scale and the A natural minor scale use only natural notes with no flats or sharps. If you start the scale on the note C, the notes in order will be C-D-E-F-G-A-B—this is the C major scale. If you play these same notes, but start on the note A, the notes in order will be A-B-C-D-E-F-G—this is the A natural minor scale. In this case, A minor is the relative minor of C major, and C major is the relative major of A minor. All major keys have a relative minor key that uses the same notes, and vice versa.

## How to Find the Relative Minor of a Major Key

You can find the relative minor of a major scale by finding that scale's sixth scale degree—the sixth note in the scale. For instance, the D major scale goes D-E-F♯-G-A-B-C♯. The sixth scale degree is B. Therefore, the relative minor of D major is the key of B minor. In fact, you can create a B minor scale by simply starting a D major scale on the note B. You'll end up using all the same notes, but you'll be playing in a different key.

## How to Find the Relative Major of a Minor Key

You can find the relative major of a minor key by using the third scale degree—the third note in the scale. For instance, the E natural minor scale uses the notes E-F♯-G-A-B-C-D. If you start that same scale on the note G, you will produce a G major scale. You will still use the same piano keys or the same finger placement on the guitar fretboard, but you'll be playing in a major key.

## What Is the Difference Between Relative Keys and Parallel Keys?

In music theory, relative scales and parallel scales are not the same thing. A relative minor scale uses all the same notes as its related major scale; a parallel minor scale has the same tonic (or first note of the scale) as its related major scale. For example: The B-flat major scale uses the notes B♭-C-D-E♭-F-G-A; its parallel minor key is B-flat minor, which has the same tonic as B-flat major but does not use the same notes. A B-flat minor scale is B♭-C-D♭-E♭-F-G♭-A♭. B-flat major’s relative minor key, on the other hand, is G minor. It uses the same notes as B-flat major, but it starts on the sixth scale degree. The G natural minor scale goes G-A-B♭-C-D-E♭-F.

Both relative keys and parallel keys are common in jazz, classical, and popular music, and each has its place in music composition and improvisation. Switching between parallel keys provides a more radical shift from major to minor and vice versa since it involves many new notes. Switching between relative keys tends to feel more subtle, since all the notes of the prior key are preserved.