Getting Started
Having established the fundamental building blocks of major scales and their corresponding key signatures, we now explore a crucial concept of tonal efficiency. A single key signature does not define just one key, but rather a pair of related keys: one major and one minor. Understanding this relationship is the first step toward analyzing how music can shift its emotional character and tonal center while using the same basic set of notes.
What You Should Be able to Do
Identify the relative minor key and its key signature for any given major key.
Identify the relative major key and its key signature for any given minor key.
Distinguish between a major key and its relative minor when analyzing notated music.
Differentiate between the sound of a major key and its relative minor in performed music.
Notate the correct key signature for any major or minor key.
Key Concepts & Analysis
Our analysis of relative keys is rooted in the idea of functional harmony, a system where chords are understood based on their relationship to a central pitch. The most important function is the tonic, which acts as the point of rest and the gravitational center of a key. While relative keys share a key signature, they are defined by two different tonics, creating two distinct harmonic worlds from the same set of notes.
Defining Relative Keys
A key in music is a system of pitches and chords organized hierarchically around a central pitch, the tonic. The key signature, a collection of sharps or flats at the beginning of a staff, indicates which notes are consistently altered from their natural state for a given piece or section.
Relative keys are a pair, one major and one minor, that share the exact same key signature. For example, C major and a minor both have a key signature with no sharps or flats. G major and e minor both have a key signature of one sharp (F#).
The Shared Pitch Collection vs. The Shift in Tonic
The reason relative keys share a key signature is that they are built from the same collection of seven diatonic pitches. The notes of the C major scale are C-D-E-F-G-A-B. The notes of the A natural minor scale are A-B-C-D-E-F-G. The pitch inventory is identical.
The critical difference lies in the tonic, or scale degree ^1. This is the pitch that provides the sense of "home" or resolution.
In C major, the tonic is C. The harmony is organized to create tension that resolves to the C major chord (I).
In a minor, the tonic is A. The harmony is organized to create tension that resolves to the a minor chord (i).
This shift in the tonal center completely changes the function of every chord built from the shared pitch collection. For example, the C major triad is the stable tonic (I) in C major, but it becomes the mediant (III) in a minor, a less stable chord that often moves toward the dominant.
How to Find Relative Keys
There are two simple and reliable methods for determining the relative major or minor of a given key.
1. Finding the Relative Minor:
To find the relative minor of any major key, start on the major key's tonic and move down three half steps.
Example: To find the relative minor of G major:
Start on G.
Down one half step is F#.
Down another half step is F.
Down a third half step is E.
The relative minor of G major is e minor. Both keys share the signature of one sharp.
Alternatively, the tonic of the relative minor is always the sixth scale degree (^6) of the major scale.
- Example: In the key of Bb major (Bb-C-D-Eb-F-G-A), the sixth scale degree is G. Therefore, the relative minor of Bb major is g minor.
2. Finding the Relative Major:
To find the relative major of any minor key, start on the minor key's tonic and move up three half steps.
Example: To find the relative major of c minor:
Start on C.
Up one half step is C#/Db.
Up another half step is D.
Up a third half step is D#/Eb.
The relative major of c minor is Eb major. Both keys share the signature of three flats.
Identifying the Key in Music
Since a key signature can represent either a major key or its relative minor, you must look at the music itself to determine the true tonic.
In Notated Music:
Check the Beginning and End: The first and, more importantly, the last chords of a piece are the strongest indicators of the tonic. A piece in C major will almost certainly end on a C major chord. A piece in a minor will end on an a minor (or sometimes A major) chord.
Look for Accidentals: This is the most decisive clue. Music in a minor key almost always uses an accidental to raise the seventh scale degree. This note is called the leading tone, and raising it creates a stronger pull toward the tonic.
- Example: A piece has a key signature of one sharp (F#), suggesting G major or e minor. If you consistently see D#s written in the music, the key is e minor. The note D# is the raised ^7 of e minor, which creates a B major dominant chord (V) that resolves powerfully to the e minor tonic (i). G major has no need for a D#.
In Performed Music:
Listen for the Tonal Center: Try to hum the pitch that feels like the ultimate point of rest. Is it the tonic of the major key or the minor key?
Identify the Quality of the Tonic: Does the "home" chord sound bright and stable (major) or dark and poignant (minor)?
Listen for the Dominant-Tonic Relationship: The sound of the dominant chord resolving to the tonic is the bedrock of tonal music. In minor keys, this cadence (V–i) has a very specific sound because the dominant chord is major (due to the raised leading tone), while the tonic chord is minor. This major-to-minor resolution is a hallmark of the minor mode.
Data & Organization Tools
The relationship between relative major and minor keys is constant. The following table shows these pairings for all key signatures up to seven sharps and seven flats.
| Key Signature | Major Key | Relative Minor |
|---|---|---|
| (no sharps/flats) | C major | a minor |
| 1 sharp (F#) | G major | e minor |
| 2 sharps (F#, C#) | D major | b minor |
| 3 sharps (F#, C#, G#) | A major | f# minor |
| 4 sharps (F#, C#, G#, D#) | E major | c# minor |
| 5 sharps (F#, C#, G#, D#, A#) | B major | g# minor |
| 6 sharps (F#, C#, G#, D#, A#, E#) | F# major | d# minor |
| 7 sharps (all notes) | C# major | a# minor |
| 1 flat (Bb) | F major | d minor |
| 2 flats (Bb, Eb) | Bb major | g minor |
| 3 flats (Bb, Eb, Ab) | Eb major | c minor |
| 4 flats (Bb, Eb, Ab, Db) | Ab major | f minor |
| 5 flats (Bb, Eb, Ab, Db, Gb) | Db major | bb minor |
| 6 flats (Bb, Eb, Ab, Db, Gb, Cb) | Gb major | eb minor |
| 7 flats (all notes) | Cb major | ab minor |
Evidence Bank
Relative Keys: A major key and a minor key that share the same key signature but have different tonics.
Tonic: The central pitch of a key (^1), which functions as the point of maximum stability and resolution.
Key Signature: The set of sharps or flats that establishes the diatonic pitch collection for a pair of relative keys.
Minor Third: The specific interval that separates the tonics of relative keys. The minor tonic is a minor third below the major tonic.
Scale Degree ^6: In a major scale, the sixth note is the tonic of its relative minor.
Raised Leading Tone: An accidental applied to the seventh scale degree of a minor scale. This is the most important analytical clue for identifying a minor key.
Dominant Function in Minor: The V chord in a minor key is almost always made major by raising the leading tone (e.g., in a minor, E-G-B becomes E-G#-B). This creates a stronger harmonic pull to the minor tonic (i).
Skill Snapshots
Functional Snapshots
The function of a chord changes dramatically depending on which of the two relative keys is established as the tonic.
The chord
a-c-e: In C major, this is the submediant triad (vi), a pre-dominant chord. In a minor, it is the tonic triad (i), the point of ultimate rest.The chord
G-B-D: In C major, this is the dominant triad (V), which creates strong tension resolving to I. In a minor (using the natural minor scale), it is the subtonic (VII), a much weaker chord.The chord
E-G#-B: This chord cannot be formed diatonically in C major. Its presence, especially its strong tendency to resolve to an a minor chord, is definitive evidence that the key is a minor, where it functions as the dominant (V).
Analytical Snapshots
Rule: A key signature of two flats (Bb, Eb) could indicate Bb major or g minor. Effect: To determine the key, find the final cadence. A resolution to a G minor triad confirms the key is g minor.
Rule: Music in a minor key frequently uses an accidental to raise ^7. Effect: In a piece with a key signature of three flats, the consistent appearance of B-naturals strongly indicates the key is c minor (where B-natural is the leading tone), not Eb major.
Rule: The tonic is the most frequent point of melodic and harmonic arrival. Effect: Aurally, if a melody repeatedly comes to rest on the pitch 'D' and the final chord feels resolved on a 'd minor' sonority, the key is likely d minor, not its relative F major.
Notational Snapshots
Baseline: To notate the key signature for A major, place three sharps (F#, C#, G#) on the staff.
Contrast: To notate the key signature for its relative, f# minor, you use the exact same key signature: three sharps (F#, C#, G#). The signature itself does not distinguish between them.
Continuity: This relationship is constant and predictable. The tonic of the minor key (f#) is always a minor third below the tonic of its relative major (A). This holds true for all key pairs.
Common Misconceptions & Clarifications
Confusing Relative vs. Parallel Keys: Relative keys share a key signature (e.g., D major and b minor). Parallel keys share a tonic (e.g., D major and d minor). They are fundamentally different relationships.
Believing the Key Signature Defines the Key: A key signature only narrows the possibilities to two keys. The music itself—through its melodic and harmonic content—establishes the one true tonic.
Ignoring Accidentals: The presence of a consistent raised leading tone is not an anomaly; it is a core feature of minor-key harmony and your most reliable clue for identifying the minor key.
Calculating the Interval Incorrectly: Remember the direction: from the major tonic, go down a minor third to find the minor tonic. From the minor tonic, go up a minor third to find the major tonic.
Summary
Every major key is paired with a relative minor key that shares an identical key signature. This shared signature exists because both keys are derived from the same seven-note diatonic collection. The defining difference between them is the tonic, or tonal center, which serves as the music's gravitational point of rest. The tonic of the relative minor is always located a minor third below the tonic of its major counterpart, corresponding to the sixth degree of the major scale. To distinguish between relative keys in practice, one must analyze the music for its harmonic goals, points of resolution, and, most critically, the presence of accidentals—specifically the raised leading tone that is characteristic of harmony in a minor key.