Find the shape. Hear the colour.
Choose a chord. See exactly how its notes fit together.
The formula
Build it step by step
Spelling, extensions & inversions
Formulas show scale degrees from the root. ♭ lowers a degree by one semitone; ♯ raises it. One semitone is one adjacent piano key, counting both black and white keys. C4 is middle C.
Extended chords here show the complete theoretical stack. Players often omit the fifth, or selected inner notes. A dominant 13th often leaves out the 11th because it rubs against the major third. A slash name shows the bass note; an inversion keeps the same chord tones but changes which one is lowest.
Open the full chord reference · changes with your chosen root
| Chord | Formula | Notes | Explore |
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Small lessons. Real understanding.
One idea, one example. Try each sound before moving on.
Build it with your own hands.
Tap piano keys to select notes. Tap a selected key again to remove it.
Choose your notes on the keyboard below.
Recognise the sound.
Listen first. Choose the chord quality you hear.
What kind of chord is this?
Press Listen, then choose an answer.
C major · root in amber, other chord notes in green
Scroll sideways for higher notes on a small screen. Tap any key to hear it. In Build mode, taps also select notes.
Quick guide & saved progress
Start with Learn, explore a sound, then try Build a chord. Ear training helps you connect the sound to its name. This reference includes 40 common and advanced chord types in all 12 pitch classes, plus alternate root spellings. Music permits many more combinations; this is a broad practical vocabulary, not every possible chord.
Sound is generated in your browser using a piano-like synthesizer, with no downloads or internet needed. Use your device volume controls if it is quiet. Progress is saved in this browser when browser storage is available. Opening the file in another browser starts a separate practice record.