Tools
Interactive circle of fifths
Tap a key on the circle and read what it holds: its sharps or flats, its seven notes, the chords built on them, its relative and its neighbours. Switch the lens to compare two keys or to see where a shift by fifths takes each note. Everything can be heard on the instrument you choose.
C major
What the circle shows
Every step clockwise is a perfect fifth up: C, then G, then D, and so on round to C again after twelve steps. Every step adds one sharp to the key signature, in a fixed order — F♯, C♯, G♯, D♯, A♯, E♯, B♯ — so a key's position on the circle is its key signature. Read the other way, every step anticlockwise is a fourth up (or a fifth down) and adds one flat: B♭, E♭, A♭, D♭, G♭, C♭, F♭.
The inner ring holds the relative minors. Each sits in the same wedge as its major, because the two share every note and every accidental: A minor has no sharps or flats exactly as C major has none. Choose the ring, and you choose major or minor.
At the bottom of the circle the two directions meet, and three positions carry two names: B and C♭, F♯ and G♭, D♭ and C♯. They are the same sounds spelled two ways — six sharps or six flats — and the tool shows both spellings so that whatever your chart says, you can find it.
Transposing with the circle
Neighbouring keys are a fifth apart, so a shift by fifths is simply a count of steps. Two steps clockwise takes every note up a tone: C major becomes D major, and every degree moves the same way — C to D, E to F♯, G to A. That is the shift a B♭ clarinet or trumpet applies when reading a concert-pitch part.
A capo works in semitones, not fifths, but the two agree at the second fret: a tone is two steps on the circle. To sound in C with the capo on the second fret, play the shapes of the key two steps anticlockwise, B♭. The transpose lens counts the steps and shows where each degree lands, so you never have to.
| Instrument | Steps on the circle | Reads in |
|---|---|---|
| Concert pitch (piano, guitar, flute) | 0 | C major |
| F horn, English horn | +1 | G major |
| B♭ clarinet, trumpet, tenor saxophone | +2 | D major |
| E♭ alto saxophone | +3 | A major |
Finding the chords of a key
The chords of a major key sit in one cluster. The tonic's wedge and its two neighbours in the outer ring are I, IV and V, the three major triads; the same three positions in the inner ring are vi, ii and iii, the three minor ones. The seventh chord, the diminished triad on the leading note, has no wedge: it is the one chord of the key the circle does not draw.
A minor key is the same cluster read from the inner ring: i, iv and v inside, III, VI and VII outside, with ii° as the chord that is missing. The chords lens lights the six wedges with their numerals, and the play button sounds I–IV–V–I in the chosen key.
Modulating with the circle
The closer two keys sit, the more they share. Neighbours have six of their seven notes in common and four of their seven triads: C major and G major both hold C, E minor, G and A minor. Any of those can be a pivot chord, heard as belonging to the first key and then to the second, which is how a smooth modulation is written.
A key and its relative share every note and differ only in which one is home. The parallel key — the same tonic in the other mode, C major and C minor — sits three steps away and shares its dominant. Keys on opposite sides of the circle share almost nothing; a modulation between them usually goes round the circle in stages, or borrows a chord from outside both. The compare lens counts the steps and lists the pivots for any pair.
The twelve keys
Every position on the circle, with its major key, its relative minor and its key signature — the same data the tool draws, computed by the same code.
| Step | Major key | Relative minor | Key signature | Accidentals |
|---|---|---|---|---|
| 0 | C major | A minor | no sharps or flats | none |
| 1 | G major | E minor | 1 sharp | F♯ |
| 2 | D major | B minor | 2 sharps | F♯ C♯ |
| 3 | A major | F♯ minor | 3 sharps | F♯ C♯ G♯ |
| 4 | E major | C♯ minor | 4 sharps | F♯ C♯ G♯ D♯ |
| 5 | B major / C♭ major | G♯ minor / A♭ minor | 5 sharps | F♯ C♯ G♯ D♯ A♯ |
| 6 | F♯ major / G♭ major | D♯ minor / E♭ minor | 6 sharps | F♯ C♯ G♯ D♯ A♯ E♯ |
| 7 | D♭ major / C♯ major | B♭ minor / A♯ minor | 5 flats | B♭ E♭ A♭ D♭ G♭ |
| 8 | A♭ major | F minor | 4 flats | B♭ E♭ A♭ D♭ |
| 9 | E♭ major | C minor | 3 flats | B♭ E♭ A♭ |
| 10 | B♭ major | G minor | 2 flats | B♭ E♭ |
| 11 | F major | D minor | 1 flat | B♭ |
Questions
- What is the circle of fifths?
- A diagram of the twelve major keys arranged so that each is a perfect fifth above the one before it, with the relative minors inside. Because each step adds one sharp or one flat, the circle lays out every key signature in order and shows at a glance which keys are close to each other and which are distant.
- Why is it called a circle of fifths?
- Each step clockwise rises by a perfect fifth: C to G, G to D, D to A. Twelve fifths later you are back on C, so the sequence closes into a circle. Read anticlockwise, each step is a perfect fourth up, which is why it is sometimes called the circle of fourths.
- How do I read a key signature from the circle?
- Count the steps from C. Clockwise, each step adds one sharp in the order F, C, G, D, A, E, B: A major is three steps round and has F♯, C♯ and G♯. Anticlockwise, each step adds one flat in the reverse order, B, E, A, D, G, C, F: E♭ major is three steps the other way and has B♭, E♭ and A♭.
- Where is the relative minor?
- In the inner ring, in the same wedge as its major. The relative minor starts on the sixth degree of the major scale, three semitones below the major tonic, and uses exactly the same notes and the same key signature: C major and A minor, G major and E minor, F major and D minor.
- Why do F♯ and G♭ share a wedge?
- They are the same sounds spelled two ways. F♯ major has six sharps and G♭ major six flats, and on a piano they are the same keys. The circle meets itself at this seam, so the neighbouring positions also carry two names: B or C♭, and D♭ or C♯. A chart may use either, so the tool shows both.
- How do I transpose with the circle?
- Count the steps between the old key and the new one, then move every chord the same number of steps in the same direction. From C to D is two steps clockwise, so G becomes A, A minor becomes B minor and F becomes G. The transpose lens does the count and shows where each degree lands.
- Which chords belong to a key?
- The six wedges around the tonic: in a major key, the tonic and its two neighbours in the outer ring give I, IV and V, and the same three positions in the inner ring give vi, ii and iii. The seventh chord of the key, the diminished triad on the leading note, has no wedge on the circle. Going the other way, find a key from its chords.
- Does the circle work for minor keys?
- Yes. The inner ring is the circle of minor keys, in the same order and with the same signatures as the majors outside them. The signature is that of the natural minor scale; the raised seventh of the harmonic minor is written as an accidental in the music, not in the key signature.