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If you’ve ever wondered why certain chords sound good together, why some key changes feel smooth while others feel jarring, or how musicians seem to instinctively know which notes will work over a chord progression, the Circle of Fifths holds the answers.

This post is about the Interactive Circle of Fifths application. To provide feedback on the application visit this link and reply in the comments. For more about the concept and construction visit the post here.

What Is the Circle of Fifths?

The Circle of Fifths is a visual map of all 12 major and minor keys, arranged to reveal the relationships between them. It’s been a cornerstone of Western music theory for nearly 300 years, and once you understand it, you’ll start seeing patterns everywhere in music.

The name comes from how the keys are arranged: as you move clockwise around the circle, each key is a “perfect fifth” higher than the one before it. A perfect fifth is the interval of seven half-steps—from C to G, from G to D, from D to A, and so on. This interval has a natural, consonant quality that our ears find pleasing, which is why it forms the backbone of so much music.

The Three Rings

The Outer Ring: Major Keys

The outer ring displays all 12 major keys. Starting from C major at the top (which has no sharps or flats), moving clockwise adds one sharp to the key signature with each step:

• C major: no sharps or flats
• G major: 1 sharp (F#)
• D major: 2 sharps (F#, C#)
• A major: 3 sharps (F#, C#, G#)
• And so on…

Moving counter-clockwise from C adds flats instead:

• F major: 1 flat (Bb)
• Bb major: 2 flats (Bb, Eb)
• Eb major: 3 flats (Bb, Eb, Ab)
• And so on…

Click any major key on the outer ring to hear its major chord and see the notes highlighted on the piano or guitar below.

The Middle Ring: Relative Minor Keys

Every major key has a “relative minor”—a minor key that shares the exact same notes and key signature. The relative minor is always found three half-steps below the major key’s root note.

For example, A minor is the relative minor of C major. Both keys use only the white keys on a piano (no sharps or flats), but they have different tonal centers. C major sounds bright and resolved when you land on C; A minor sounds darker and resolved when you land on A.

This relationship is powerful for songwriters. You can shift between a major key and its relative minor within a song to change the emotional color while keeping all the notes familiar.

The Inner Ring: Scales and Chords

The inner ring changes based on the dropdown menu selection:

Diminished shows the diminished triad built on the seventh degree of the scale. This tense, unstable chord naturally wants to resolve and is useful for creating movement in chord progressions.

Pentatonic displays the five-note pentatonic scale. This scale omits the two notes that create the most tension in the full scale, making it incredibly versatile for melodies and improvisation. The major pentatonic works over major chords; the minor pentatonic is the foundation of blues and rock soloing.

Diatonic shows the complete seven-note major or minor scale. These are the notes that “belong” to the key and form the basis for melody and harmony.

Click the inner ring when Pentatonic or Diatonic is selected to hear the scale played ascending and descending.

Key Signatures on the Staff

The small staff notations around the circle show each key’s signature—the sharps or flats that apply throughout a piece in that key. Rather than writing a sharp or flat symbol every time you encounter that note, the key signature tells you once at the beginning: “Every F in this piece is F#” (in G major, for instance).

Notice the elegant pattern: sharps accumulate in a specific order (F#, C#, G#, D#, A#, E#) and flats in the reverse order (Bb, Eb, Ab, Db, Gb, Cb). Musicians memorize these patterns, making it quick to identify any key at a glance.

The Harmonized Scale

Below the circle, the harmonized scale staff shows something essential: the seven chords that naturally occur within a key.

When you build a triad on each note of a major scale using only notes from that scale, you get a specific pattern of chord qualities:

Scale Degree	Roman Numeral	Quality	Example in C
1st	I	Major	C
2nd	ii	Minor	Dm
3rd	iii	Minor	Em
4th	IV	Major	F
5th	V	Major	G
6th	vi	Minor	Am
7th	vii°	Diminished	B°

This pattern—Major, minor, minor, Major, Major, minor, diminished—holds true for every major key. The Roman numerals (uppercase for major, lowercase for minor) let musicians discuss chord progressions in a universal language. When someone says “it’s a I-IV-V progression,” that means the same chord relationships whether you’re in C major (C-F-G) or E major (E-A-B).

Click any chord on the harmonized staff to hear it and see its notes on the instrument display.

For minor keys, the pattern shifts to: minor, diminished, Major, minor, minor, Major, Major (i, ii°, III, iv, v, VI, VII).

Why Adjacent Keys Matter

When you select a key, notice that the adjacent keys on either side are highlighted. These are your closest musical neighbors—the keys most closely related to your current key.

Moving one position clockwise adds one sharp (or removes one flat). Moving counter-clockwise adds one flat (or removes one sharp). These neighboring keys share six of their seven notes with your current key, differing by only one note.

This is why chord progressions often “borrow” chords from neighboring keys—they fit naturally because most of the notes are already part of your key. It’s also why modulating (changing keys) to an adjacent key sounds smooth, while jumping to a distant key on the circle sounds dramatic or surprising.

The Piano and Guitar Views

Toggle between piano and guitar displays to see how scales and chords map onto each instrument.

Color coding:

• Green indicates the root note (the note the chord or scale is built on)
• Blue marks chord tones—the 1st, 3rd, and 5th that form the triad
• Orange shows additional scale tones when viewing pentatonic or diatonic scales

On guitar, you’ll notice that scale patterns repeat in predictable shapes due to the instrument’s tuning. On piano, the relationship between black and white keys makes certain keys feel quite different under your fingers, even though the theoretical relationships are identical.

Practical Applications

Finding chords that work together: Any chord from the harmonized scale will sound good with any other chord from that same key. The I, IV, and V chords form the backbone of countless songs. Adding the vi chord gives you the ubiquitous I-V-vi-IV progression heard in hundreds of pop songs.

Transposing songs: If a song is too high or low for your voice, use the circle to find a new key. The relationships between chords stay the same—a IV chord is still a IV chord—only the letter names change.

Understanding songs you hear: When you recognize that a song moves from I to vi to IV to V, you’re hearing the underlying structure that makes it work. This pattern recognition accelerates learning new music.

Improvising and soloing: The pentatonic scale is your safety net. Staying within those five notes virtually guarantees you won’t hit a “wrong” note over chords in that key.

Writing chord progressions: Experiment with the harmonized scale. Try moving between chords that share notes (like C and Am, which share C and E). Try the tension of the vii° chord resolving to I. Try borrowing the IV chord from the parallel minor for a melancholy color.

A Tool for Exploration

The Circle of Fifths isn’t just a reference chart—it’s a tool for discovery. Click around, listen to how keys relate to each other, notice which chords share notes, hear how scales differ between major and minor.

Music theory sometimes gets a reputation for being dry or restrictive, but it’s really a map of possibilities. The Circle of Fifths shows you why certain things work, freeing you to make informed creative choices rather than stumbling in the dark.

Whether you’re writing songs, learning an instrument, studying for a theory exam, or just curious about how music fits together, spend some time with the circle. The patterns you discover will start appearing everywhere you listen.