Circle o Fifths: Music Theory

Grab your instrument and hear, learn, and write music with the circle of fifths! This handy music practice and theory tool can be a game changer for learning songs, writing your own, and understanding how chords fit together.

NEW in 2.0: Piano mode and a chord progression builder!

Switch between guitar and piano on the fly — chord diagrams, sounds, and strumming all swap to match. Then jump to the new progressions tab to build your own chord progressions, pick a tempo, and hear them played back with realistic strumming patterns.

Features:
• 3 full rings with support for all major and minor keys
• 36 interactive notes/chords on the circle
• NEW! Toggle between guitar and piano modes — affects both sounds and diagrams
• NEW! Synthesized piano with rich, multi-voice triads
• 36 real guitar audio recordings of every chord on the circle
• 36 guitar chord charts — just tap and hold to learn
• NEW! Piano chord diagrams with highlighted notes on a keyboard
• Color coding to help you reference and learn the note/chord you're playing
• Chords tab to see all chords in each key, with major/minor relationships
• NEW! Progressions tab — build your own progressions and hear them play back
- Pick any major or minor key (24 total)
- Tap I, ii, iii, IV, V, vi, vii° to add chords to your track
- Tempo control (60–180 BPM) and loop for practice
- Strum patterns: Whole, Quarter, Eighth, Folk, Rock
- Built-in metronome
• NEW! iPad-optimized layout — the whole UI scales beautifully on every device

The outside ring of the circle has all the major keys. Tap any of them to hear and change the key. The color coding tells you which number each chord is. The middle ring has all the minor keys, and the inner ring has the diminished chords. Tap any chord to hear it, or tap and hold to see how to play it on guitar or piano!

If you're playing in a major key, use the color coding up top to understand the chord relationships. If you're playing in a minor key, use the color coding on the bottom.

Use the Chords tab to play songs in any key, transpose on the fly, and see major/minor key relationships. Use the Progressions tab to compose, practice over a loop, or hear common progressions like I-IV-V or ii-V-I in any key.