Getting Started
Understanding how to build scales and chords within a single key is a foundational skill. The next step is to understand how different keys relate to one another. This knowledge is essential for analyzing longer musical works, which rarely remain in one key from beginning to end, and provides a map for the harmonic journey a composer creates.
What You Should Be able to Do
Identify the relationship between two given keys as parallel, closely related, or distantly related.
Given a starting key, name its parallel key.
Given a starting key, list all five of its closely related keys.
Describe the key relationship between two sections of notated music.
Analyze a musical score to locate and label shifts to new keys.
Key Concepts & Analysis
The relationship between any two keys is defined by two fundamental components: their shared tonic and the similarity of their key signatures. These factors determine whether a key is considered parallel, closely related, or distantly related to a home key. Analyzing these relationships is the first step in understanding the large-scale harmonic structure of a piece.
Defining Key Relationships
A tonic is the central pitch around which a scale and a key are built; it is scale degree ^1. A key signature is the collection of sharps or flats at the beginning of a musical staff that indicates which notes are to be consistently raised or lowered. The proximity of two key signatures—how many accidentals they differ by—is a primary measure of their relationship. An accidental is a symbol (such as a sharp, flat, or natural) that modifies the pitch of a note.
Parallel Keys
A parallel key relationship exists between a major and a minor key that share the same tonic. For example, C major and c minor are parallel keys because they both have a tonic of C. This relationship is also known as a "parallel major/minor" or "tonic major/minor."
Shared Element: Tonic pitch (e.g., C).
Different Element: Key signature and mode. C major has no sharps or flats, while c minor has three flats (B♭, E♭, A♭).
The shift between parallel keys is a powerful expressive device. Because the tonic remains the same, the listener feels a strong sense of connection, but the change in mode from major to minor (or vice versa) creates a dramatic change in color and mood.
Closely Related Keys
Closely related keys are those whose key signatures differ from the home key by no more than one accidental. A piece of music is most likely to modulate, or shift, to one of these keys. For any given major or minor key, there are exactly five closely related keys.
These five keys can be found systematically:
The Relative Major/Minor: The key that shares the exact same key signature. (0 accidental difference).
The Dominant: The key built on the fifth scale degree (^5) of the home key. Its key signature has one more sharp or one less flat.
The Subdominant: The key built on the fourth scale degree (^4) of the home key. Its key signature has one more flat or one less sharp.
The Relative of the Dominant: The relative major or minor of the dominant key.
The Relative of the Subdominant: The relative major or minor of the subdominant key.
For example, let's find the five closely related keys to C major (no sharps/flats):
Relative: a minor (0 sharps/flats)
Dominant: G major (1 sharp)
Subdominant: F major (1 flat)
Relative of Dominant (G major): e minor (1 sharp)
Relative of Subdominant (F major): d minor (1 flat)
Notice that the tonics of these five keys (a, G, F, e, d) correspond to the diatonic scale degrees of C major, excluding the tonic (^1) and the leading tone (^7). The triads built on these scale degrees (vi, V, IV, iii, ii) are the primary chords in the original key.
Distantly Related Keys
A distantly related key is any key that is not parallel and not closely related to the home key. This means its key signature differs from the home key by two or more accidentals. For example, C major (0 sharps) and D major (2 sharps) are distantly related. Likewise, C major and A-flat major (4 flats) are distantly related.
While modulations to closely related keys are common and create smooth transitions, modulations to distant keys are less frequent and often used for dramatic effect, surprise, or to signify a major structural division in a musical form.
Data & Organization Tools
The following table provides a systematic method for identifying the five closely related keys for any major or minor home key.
| Relationship to Home Key | How to Find It | Example: G major (1♯) | Example: e minor (1♯) |
|---|---|---|---|
| Relative | Same key signature, different tonic | e minor | G major |
| Dominant | Add one sharp / remove one flat | D major | b minor |
| Subdominant | Add one flat / remove one sharp | C major | a minor |
| Relative of Dominant | Relative of the dominant key | b minor | D major |
| Relative of Subdominant | Relative of the subdominant key | a minor | C major |
Evidence Bank
Tonic: The foundational pitch (^1) that defines a key's center of gravity.
Key Signature: The set of sharps or flats that establishes the diatonic pitches for a key.
Parallel Key: A key with the same tonic but a different mode and key signature (e.g., D major and d minor).
Relative Key: A key with the same key signature but a different tonic (e.g., D major and b minor). It is the most closely related key.
Closely Related Key: A key whose signature differs by at most one accidental from the home key. These are the most common destinations for modulation.
Dominant Key: The key built on ^5 of the home key. Its signature is one step sharper on the circle of fifths.
Subdominant Key: The key built on ^4 of the home key. Its signature is one step flatter on the circle of fifths.
Distant Key Relationship: Any relationship between keys whose signatures differ by two or more accidentals (and are not parallel).
Analytical Snapshots
Identification: Given the home key of B-flat major (2 flats), the key of b-flat minor (5 flats) is its parallel key. They share the tonic B♭ but have different key signatures and modes.
Proximity: Given the home key of B-flat major (2 flats), the key of F major (1 flat) is a closely related key. Its key signature differs by only one accidental, and its tonic is the dominant (^5) of B-flat major.
Distance: Given the home key of B-flat major (2 flats), the key of E major (4 sharps) is a distantly related key. Their key signatures are separated by six accidentals (2 flats to 4 sharps), creating a remote harmonic relationship.
Common Misconceptions & Clarifications
Parallel vs. Relative Keys: Do not confuse parallel and relative keys. Parallel keys share a tonic (C major / c minor). Relative keys share a key signature (C major / a minor).
Counting Accidentals: The "one accidental" rule for closely related keys refers to a one-step change in the key signature (e.g., from 2 sharps to 3 sharps, or 2 sharps to 1 sharp). It is not the absolute number of sharps or flats.
The Dominant Key of a Minor Key: The dominant key of a minor key is also minor. For example, in a minor, the dominant scale degree is E. The key built on that tonic, e minor, is the closely related dominant key, not E major.
All Diatonic Chords as Keys: While the tonics of closely related keys correspond to diatonic chords (ii, iii, IV, V, vi), the key built on the leading tone (^7) is not closely related. For C major, the leading-tone triad is b diminished, and the key of B major (5 sharps) is distantly related.
Summary
Key relationships provide a framework for understanding the harmonic language of tonal music. These relationships are categorized into three types based on the tonic and key signature. Parallel keys share a tonic but have different modes. Closely related keys have key signatures that differ by no more than one accidental, representing the most common and smoothest tonal shifts. All other relationships are considered distantly related and are used for more dramatic harmonic effects. By being able to identify these relationships in both notated and performed music, you can better trace the structural and expressive path a composer creates.