Free · No account · No subscription
Music theory you can hear, play and use.
A free course from first principles to advanced harmony, and tools for the questions a player actually has. Every idea is a sound before it is a word, played on piano, guitar, bass or ukulele.
C major · C · Dm · Em · F · G · Am · B°
Tap a key to hear it on your instrument.
Tools
Have a real question? Ask a tool.
Free tools for the moment a song is in front of you. Every answer can be heard on your instrument.
Key finder
What key is this song in? Enter the chords you have and see which keys they fit.
Chord identifier
What chord is this? Tap or type the notes and get its name, inversions and aliases.
Chord transposer
Song in the wrong key for your voice? Paste the chords and read them back in any key.
Roman numeral converter
Chords to roman numerals, or back? Type a progression and read it in any key.
Scale finder
Which scale fits this riff? Pick its notes and find every scale that contains them.
Interval calculator
How far apart are two notes? Name the interval between them, and hear it.
The course
Start at the beginning
From first principles to advanced harmony, in order. Each chapter lists what it assumes and links straight back to it — with the sound attached — so you can start in the middle without guessing what you have missed.
The course, part by part
Lessons
Or take one idea at a time
Self-contained explanations of one idea each. Start anywhere.
Musical Notes
What a note is, why the octave repeats, and how twelve of them make the whole system.
Reading Sheet Music Fast
Landmark notes and pattern reading, so the staff stops being a lookup table.
Why Scales Matter
A scale is the set of notes a song draws from. Know it, and the melody makes sense.
The Circle of Fifths
How to read the circle, and how it hands you key signatures and chord changes.
Modes: Dorian, Lydian, Mixolydian
Three modes, one formula each, and a famous song that shows what each one sounds like.
Negative Harmony
Flip a progression around its axis and hear what the mirror image sounds like.
Reference
Look anything up
Every interval, chord, scale and progression has a page of its own — shown on your instrument, and playable.
Intervals Explorer
Unison to augmented thirteenth, on keyboard and fretboard.
Chord Library
Triads to altered jazz voicings, on piano and guitar.
Scales & Modes
Major and minor to the modes and beyond, on both instruments.
Chord Progressions
The sequences songs are built from, in roman numerals.
Hear one of each
Questions
- What can I learn here?
- Music theory from first principles to advanced harmony: a course in order, standalone lessons, and a reference page for every interval, chord, scale and progression. Real songs are cited throughout, each with a note on where in the recording to listen.
- Do I need to read music to start?
- No. Notation has a chapter of its own and is not a prerequisite for any other, so you can go straight to intervals, scales or harmony without it. Every example is playable and drawn on your instrument. If you already read music, the staff is one of the views.
- Can I hear the examples?
- Yes. Every interval, chord, scale and progression on the site can be played, and any note or chord named in a sentence is clickable. Whatever sounds is drawn at the same moment on the instrument you chose — piano, guitar, bass or ukulele.
- Are there tools, or is it all lessons?
- Both. The tools answer the practical questions: find a song's key from its chords, name a chord from its notes, transpose a progression into any key, read the circle of fifths, find the scale a riff fits, calculate an interval, and turn chords into roman numerals or back. Every result can be played on your instrument.
- Is this useful for guitar, or is it all piano?
- Chapters draw no instrument of their own. You choose piano, guitar, bass or ukulele once, and every example, scale shape and chord on the site is redrawn on it. The explanations do not change; only the picture does.
- Does it include ear training?
- Yes, as part of the course rather than a separate app. Ear training has a chapter of its own early on, and from there every chapter includes something to identify by ear. Wrong answers are explained per option: what you probably heard, what it was, and the difference.
- How is this different from a music theory app?
- It is a course and a reference, not a drill loop. There is no score, no streak and no daily goal; the only thing stored is which chapters you have opened. Every check explains all of its options, including the ones you did not choose.
Start with chapter one
Free, no account, and no reading required. Chapter one assumes you know nothing. Or skip the course and go straight to a tool.