Mathematics, Music, Web Design

Magic Circle of Fifths

Magic Circle analyzes your piano play and instantly shows what notes and chords you are playing. Use it for improvisation, composition or fun.

DOWNLOAD Magic Circle for Mac OSX (2579) | | Magic Circle for Windows (5415) source code Magic Circle source code (4121)

Over the past weeks I have been working on an Processing sketch that helps you to play piano by giving you insight in what you are playing. It is based on the idea of the Circle of Fifths.

Show me!

A friend of mine, Freek de Graaf is a lot better at playing the piano so I conveniently used one of his arrangement to demonstrate the awesomeness of Magic Circle. Thanx Freek :)

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Magic Circle showing a chord

About the Circle of Fifths

For those of you who have never heard of it: in the circle of fifths notes are arranged by an interval of 5 tones clockwise on a circle. So, if we start from C at the top, the next notes are G, D, A, E, B, F#(Gb), Db, Ab, Eb, Bb and F.

Musical relatives & key

Because of the way the notes are arranged on the circle, it has some pretty useful properties. Notes close to each other on the circle are musically related, i.e. they will probably sound good when played together. also, seven notes next to each other make up a scale. If we take the C note, the F on the left and the G, D, A, E and B we have all the notes on the scale of C major. Magic Circle shows these notes conveniently grouped into a tonic structure: all the notes in the current key with a white line around them.

Scale of C


Understand what you are playing

Often when you are improvising you do not consciously know what chords you are playing. Magic Circle helps you to get direct feedback on the structure of your improvisation. It can detect a number of different chords and will show you the correct names for them.

Take a look at some of the chords that are played in the video:

Visual cues for chord recognition

Because of the layout of notes, a certain chord always has a specific shape. For example, the minor and major triads have a squashed triangle shape and are mirrored versions of each other. Major 7th chords look like a trapezoid. Diminished and augmented chords are symmetrical squares and triangles. By playing the chords and associating the shapes with the sounds and emotional quality of the chord you can help yourself understand what you are playing.

F Major 7th

Help by composing songs

Even better than only recognizing the structure in the music you are playing is teaching yourself the ability to compose music visually. Recognize the chords and link them to the emotional quality of the sound and then learn to recognize chord progressions as changes in the visual pattern. One chord resolves into another, sometimes sounding like going away (from C to Dm for example) or coming back home (G7 – C). These movements are directly related to movements on the circle, where going going away further from the tonic is also emotionally perceived as such and taking steps towards the tonic creates the feeling of resolvement.

In Jazz, chord progressions are often very regular / structured and will look like a series of steps counter-clockwise on the circle. Take for example the intro of the Realbook classic ‘Have you met Miss Jones’ by Rogers and Hart. The chord progression is as follows:

Cmaj7 – C#dim – Dm7 – G7 – Em7 – Am7 – Dm7 – G7 – Cmaj7

The last part from Em7 is just working your way down the circle counter-clockwise until you end up at the tonic, in this case C.

And much more

There are many more uses of the circle in composing songs. I will try to write some posts on these different aspects while I learn more about composition myself. So please subscribe by email or with a news reader, or check my youtube channel for updates.

Features of Magic Circle

  • Live visual representation of the notes you are playing
  • A presentation mode for impressing your friends
  • Live chord recognition of most western (Pop, Rock & Jazz) chords
  • Change keys easily with a foot pedal (Midi channel C00)
  • Display of overtones of the notes you play
  • May change your life and the way you learn to play piano forever


All source code to the Magic Circle processing application is freely available under the Creative Commons Non-commercial licence. Please feel free to make your own versions, improve upon my code, share your own creations and enjoy learning about playing piano!

Magic Circle for Mac OSX (2579) (not tested!)

Magic Circle for Windows (5415) (not tested!)

Magic Circle for Linux (1021) (what do you think?)

For the adventurous, you can also download the source code. Use at your own risk, but enjoy, extend and share.

Magic Circle source code (4121) (.zip, 5.6 MB)

You will need

Processing (for running the source code sketch)

RWMidi Library

A midi-enabled keyboard (you can even use a virtual keyboard if you don’t have the real deal)


I have been trying to learn the piano over a year now without taking lessons from a professional teacher. It has been quite an effort, but if you like to do something bad enough, you will find a way ;) . I have mostly used the internet as my source of lessons, inspiration and teaching aids.

Magic Circle was inspired by the Interactive Circle of Fifths by Rand Scullard. Many thanks to him for his incredibly useful HTML implementation of the circle and his detailed explanation. I’d urge you to take a look at his site, it’s worth it!

My neighbour and friend Freek de Graaf who is a talented pianist and composer has given me the opportunity to test the system with somebody who can actually play and has given me helpful tips and advice. Thanks Freek!

A lot of tricks on playing Jazz paino have been given to me in MusicGuru12′s excellent online piano tutorials. Thanks man!

Wikipedia provides a lot of excellent articles on music theory. Especially the articles on chords, progressions, mathematics of music and modes.

Play and enjoy!

Learning an instrument for me is a combination of perseverance, fun, patience, the occasional frustration and a developing emotional binding with my instrument. I have played Cello for 14 years and I was up for something new, so I started to teach myself piano. And to learn you have to practice, practice, practice. Everybody knows that, but if you find a way to make this practice fun and engaging, you are already halfway there!

So let me know what you are doing with this little tool and I hope you will keep coming back for more info and insights from a budding pianist.

If you like (or love) Magic Circle, please consider donating $30 or a smaller amount to help me continue development of this little app. [donate]

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