Relative key
In music theory, relative keys are major and minor scales or tonalities that share the same key signature, consisting of the identical set of pitches but centered on different tonic notes.[1] The relative minor of a major key begins on the sixth degree of the major scale, while the relative major of a minor key begins a minor third above the minor tonic.[2] For instance, A minor is the relative minor of C major, as both use no sharps or flats and derive from the same diatonic collection, with A minor's tonic three half steps below C.[3] This relationship forms a cornerstone of Western tonal harmony, enabling composers to modulate between major and minor modes without altering accidentals, thus creating contrast in mood—typically brighter in major and more somber in minor—while maintaining diatonic coherence.[4] Relative keys appear frequently in classical, jazz, and popular music for structural purposes, such as bridging sections in sonata form or enhancing emotional depth through pivot chords common to both tonalities.[5] Understanding them is essential for analyzing chord progressions, transposing works, and composing, as they reveal how a single key signature supports dual tonal centers.[6] In practice, every major key has one relative minor, and vice versa, forming 12 such pairs across the chromatic scale, excluding enharmonic equivalents.[7]Fundamentals
Definition
In music theory, relative keys refer to pairs of major and minor keys that share the identical key signature, meaning they employ the same set of pitches, but establish their tonal centers on different scale degrees.[7] The major key begins on the tonic (first scale degree), while its relative minor commences on the sixth scale degree of that major scale, utilizing the natural minor scale form.[7] Conversely, the relative major of a given minor key is constructed starting from the third scale degree of the minor scale.[7] This relationship ensures that both keys draw from the same collection of notes without requiring additional accidentals beyond the shared signature.[8] The core distinction between relative keys lies in their emphasis on different roots as the tonal center, despite the common pitch content, which allows composers to shift emotional or structural focus within the same diatonic framework.[9] For instance, the relative minor highlights a minor third below the major key's tonic as its new root, creating a sense of relatedness while altering the mode's character from bright and stable (major) to more introspective or tense (minor).[7] This shared pitch collection facilitates seamless transitions in composition, as no new notes are introduced.[8] A classic example is the pair of C major and A minor, both featuring no sharps or flats in their key signatures. The C major scale consists of the notes C-D-E-F-G-A-B, with C as the tonic.[7] In contrast, the A minor scale rearranges these same pitches starting from A: A-B-C-D-E-F-G, establishing A as the tonal center and deriving from the sixth degree of the C major scale.[7] This illustrates how relative keys maintain harmonic compatibility while varying the perceived key through root emphasis.Relationship to Key Signatures
Relative keys are defined by their shared key signatures, meaning that each pair consists of a major key and its corresponding minor key (or vice versa) that employ identical sets of sharps or flats. This structural equivalence ensures that the pitch collections derived from their scales are the same, differing only in the choice of tonic note. For instance, the key of G major, with a key signature of one sharp (F♯), corresponds to E minor, which uses the identical signature of one sharp (F♯).[6][9] The key signature fundamentally determines the accidentals present in the diatonic scale for both keys in a relative pair, establishing a common set of seven pitches. In the natural minor scale of the relative minor, these accidentals match exactly those of the major scale, without requiring any additional alterations such as raised leading tones or lowered submediants that might appear in harmonic or melodic minor forms. This alignment is evident in examples like C major and A minor, both of which have no sharps or flats, allowing seamless use of the same notational framework.[3][10] Consequently, transitions between relative keys in composition or analysis require no changes to the key signature, preserving the notational consistency and avoiding the enharmonic adjustments necessary for shifts to non-relative keys. This property underscores the relational harmony inherent in the tonal system, where the shared signature facilitates fluid exploration of major and minor modalities within the same pitch framework.[11][12]Identification Methods
Relative Minor of a Major Key
In the major scale, the tonic note of the relative minor is the sixth scale degree, known as the submediant.[6] This sixth degree becomes the starting point for the natural minor scale, which forms the basis of the relative minor key.[13] The interval between the tonic of the major key and the tonic of its relative minor is a minor third downward (three semitones) or, equivalently, a major sixth upward.[3] To identify the relative minor tonic, lower the major key's tonic by a minor third; for instance, starting from C major, descending three half-steps from C leads to A, establishing A minor as the relative minor.[3] These relative keys share the same key signature.[7] The following table provides examples for all twelve major keys and their relative minors, based on the natural minor scale:Relative Major of a Minor Key
In the natural minor scale, the tonic of the relative major key corresponds to the third scale degree, referred to as the mediant.[9] This relationship positions the relative major tonic a minor third above the minor tonic—or three half steps upward—or equivalently, a major sixth below.[7] The formula for identifying the relative major involves raising the minor key's tonic by a minor third; for instance, starting from A minor and ascending three half steps arrives at C as the tonic of C major.[15] The following table lists the relative major keys for all twelve minor keys, based on this interval structure and shared key signatures:| Minor Key | Relative Major Key |
|---|---|
| A minor | C major |
| B♭ minor | D♭ major |
| B minor | D major |
| C minor | E♭ major |
| C♯ minor | E major |
| D minor | F major |
| D♯ minor | F♯ major |
| E minor | G major |
| F minor | A♭ major |
| F♯ minor | A major |
| G minor | B♭ major |
| G♯ minor | B major |