Relative and parallel keys

C major and A minor share a key signature with no sharps or flats; C major and C minor share a tonic but are three flats apart.

Two kinds of relatives

Every major key has two close minor partners. The relative minor shares its key signature: the same notes with a different home. The parallel minor shares its tonic: the same home with different notes. C major's relative minor is A minor, with no sharps or flats; its parallel minor is C minor, with three flats. Both relationships matter, but they answer different questions: which notes, and which home.

To find the relative minor, count three half steps down from the major tonic: C, B, B♭, A gives A minor. You can also use scale degrees: the relative minor starts on the 6th degree of the major scale. Going the other way, the relative major is three half steps up from the minor tonic, on its 3rd degree. On the circle of fifths the relative minor sits directly inside its major, which is why the two share a slice of the ring.

Spell the result with the right letter. Three half steps below D♭ is a key that could be called B♭ or A♯, but only B♭ minor has five flats like D♭ major; A♯ minor would need seven sharps. A relative pair always uses the same kind of accidental, and the minor tonic is always a third, three letter names, below the major tonic: D♭, C, B♭.

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Pick an outer key, then press "Major ↔ relative minor" to jump to the inner ring. The key signature on the staff stays the same; only the tonic and the scale change.

Parallel keys: same home, new colour

Parallel keys share a tonic, and their signatures always differ by three steps in the flat direction. C major has none and C minor three flats; D major has two sharps and D minor one flat; A major has three sharps and A minor none. Those three steps are the natural minor's lowered 3rd, 6th and 7th. Switching from a major key to its parallel minor keeps the same home note and changes the colour of the music.

Major or minor? Reading a piece

A key signature narrows a piece down to two keys, a major key and its relative minor. To choose between them, look at the first and last notes, especially in the bass, because pieces usually begin and end on the tonic. Then look for an accidental that keeps returning a half step below one of the two candidates. In a piece with no sharps or flats in the signature, frequent G♯s point to A minor rather than C major. Open Music Theory shows a song by Louise Reichardt (1779 to 1826) with four flats: the voice and the lowest piano note both begin on F, so the song is in F minor rather than A♭ major.

BackgroundIn 1722 Johann Sebastian Bach dated a book of 24 preludes and fugues for keyboard, one pair in every major and minor key. He ordered them in pairs of parallel keys climbing by half steps: C major, C minor, C♯ major, C♯ minor, D major, and so on up to B minor. About twenty years later he compiled a second book on the same plan. The title, The Well-Tempered Clavier, refers to a keyboard tuned well enough that all 24 keys can be played.

C major	A minor (no sharps or flats)
G major	E minor (1 sharp)
D major	B minor (2 sharps)
A major	F♯ minor (3 sharps)
F major	D minor (1 flat)
B♭ major	G minor (2 flats)
E♭ major	C minor (3 flats)

What is the relative minor of G major?
- E minor
- G minor
- D minor
- B minor
What is the parallel minor of D major?
- D minor
- B minor
- F♯ minor
- A minor
What is the relative major of D minor?
- F major
- D major
- B♭ major
- A major
The relative minor starts on which degree of the major scale?
- 6th
- 3rd
- 5th
- 4th
How many half steps below the major tonic is its relative minor tonic?
What is the relative minor of D♭ major?
- B♭ minor
- A♯ minor
- D♭ minor
- F minor
How many flats does C minor have?
A major has three sharps. How many sharps or flats does A minor have?
- None
- Three flats
- Three sharps
- One sharp
A piece has one sharp, starts and ends on E, and often uses D♯. Its key is probably…
- E minor
- G major
- E major
- D major
Which pair are relative keys?
- B♭ major and G minor
- B♭ major and B♭ minor
- G major and G minor
- B♭ major and D minor
In what order did Bach arrange Book 1 of The Well-Tempered Clavier?
- Major then parallel minor, rising by half steps
- Around the circle of fifths
- All majors, then all minors
- In order of difficulty
A signature narrows a piece to which two keys?
- A major key and its relative minor
- A major key and its parallel minor
- Two major keys a fifth apart
- Two minor keys a fifth apart

Key points

Relative keys share a key signature; the minor tonic is 3 half steps below.
Parallel keys share a tonic; signatures differ by three steps toward flats.
Spell relatives with the same kind of accidental (D♭ major / B♭ minor).
To find the key, check the first and last notes and any recurring raised 7th.

Sources for this course (5)

Open Music Theory 2e (Viva Pressbooks; ideas only, no sentences copied): "Major Scales, Scale Degrees, and Key Signatures" (W-W-H-W-W-W-H, scale named for first note incl. accidental, scale-degree numbers with carets, do re mi fa sol la ti, tonic/supertonic/mediant/subdominant/dominant/submediant/leading tone and how the names were derived, clef-key-time order, order of sharps F C G D A E B and flats B E A D G C F, last sharp a half step below the tonic, second-to-last flat is the tonic, C and F memorised, C♭ seven flats and C♯ seven sharps, circle of fifths with enharmonic keys at 5, 6 and 7 o'clock; viva.pressbooks.pub/openmusictheory/chapter/major-scales/) and "Minor Scales, Scale Degrees, and Key Signatures" (natural W-H-W-W-H-W-W, harmonic W-H-W-W-H-3H-H, melodic up W-H-W-W-W-W-H and down = natural, lowered 3 6 7 / 3 6 / 3, me le te, subtonic, parallel and relative, relative minor three half steps below, D♭ major and B♭ minor not A♯ minor, three flavours of the same key, first and last notes and the Louise Reichardt song in F minor; viva.pressbooks.pub/openmusictheory/chapter/minor-scales/)
musictheory.net lessons 21-24 used as a cross-check only. Wikipedia "Circle of fifths" (Diletskii Grammatika 1677, Heinichen Musicalischer Circul 1711 and 1728, relative minor placed beside its major; en.wikipedia.org/wiki/Circle_of_fifths) and C. R. Jensen, "A Theoretical Work of Late Seventeenth-Century Muscovy: Nikolai Diletskii's Grammatika and the Earliest Circle of Fifths", JAMS 45/2 (1992)
abstract (surviving variants Smolensk 1677, Moscow 1679 and 1681; doi.org/10.2307/831450)
Wikipedia "The Well-Tempered Clavier" (Book 1 autograph dated 1722, 24 keys, C major then C minor then up by half steps; en.wikipedia.org/wiki/The_Well-Tempered_Clavier)
Wikipedia "Solfège" and "Guido of Arezzo" (ut re mi fa sol la from Ut queant laxis, 11th century, ut became do in 17th-century Italy, si added later, ti from Sarah Glover in the 19th century, fixed do in Romance-language countries; en.wikipedia.org/wiki/Solf%C3%A8ge).

Checked: 2026-10-17