Music Theory
See and hear scales, chords, intervals and keys, spelled the way they're written, plus guitar chords, progressions and a chord transposer. Learn more
Chord Builder/Identifier
Build 27 chord types from any root, or name the chord your notes make.
Chord Progression Generator
Hear and copy common progressions in any key, correctly spelled.
Circle of Fifths Reference
An interactive circle of fifths with signatures, scales and main chords.
Guitar Chord Chart
40 guitar chord diagrams with fingers, barre chords and a strum.
Interval Calculator
Name the interval between two notes, including compound intervals.
Key Signature Finder
Sharps or flats in any key, drawn on the staff, with the relative key.
Note Frequency Reference
Exact Hz for any note, at 440 Hz or another tuning, with playback.
Scale Finder
Hear and see any scale or mode, correctly spelled, with scale degrees.
Transposition Tool
Transpose chords or a whole chord sheet, with key-aware spelling and capo tips.
Free music theory tools for players, students and songwriters
Whether you're working towards a grade exam, writing your first song or trying to work out what the guitarist just played, these tools give you answers you can see and hear. Every note is spelled the way it's written in sheet music, so the Scale Finder shows F major with a B♭ rather than an A♯, and the Chord Builder & Identifier spells all 27 chord types correctly from any root, or names the chord made by a set of notes, inversions and slash chords included. The Interval Calculator tells a minor 3rd from an augmented 2nd, and the Key Signature Finder draws the sharps or flats on the treble and bass staves.
For songwriting, the Chord Progression Generator plays classic progressions such as I–V–vi–IV and ii–V–I in any key, and the Circle of Fifths shows which chords and keys sit naturally together. Guitarists can look up 40 shapes, from open chords to barre chords, in the Guitar Chord Chart, and move a whole chord sheet into a better key for a singer with the Transposition Tool, which also suggests a capo position. The Note Frequency Reference gives the exact pitch of every note at 440 Hz or another tuning standard.
Questions and answers
- Why does the Scale Finder show B♭ instead of A♯ in F major?
- They're the same key on a piano, but in written music each letter appears once in a major or minor scale. F major already has an A, so the fourth note has to be a kind of B, which makes it B♭. Spelling notes this way is what makes key signatures, chord names and sheet music readable, and it's why every tool here uses letter-based spelling rather than always choosing sharps.
- What's the difference between the Chord Builder and the Chord Progression Generator?
- The Chord Builder works on one chord at a time: choose a root and a chord type to see and hear its notes, or switch to Identify mode to name the chord a set of notes makes. The Chord Progression Generator works on a key: it builds the chords that belong in that key and strings them into common progressions, so you get a ready-made sequence for a song with the right chord qualities and spelling.
- Should I use the Circle of Fifths or the Key Signature Finder?
- Use the Key Signature Finder when you want the facts about one key: its sharps or flats in order, drawn on the staff, plus its relative major or minor and scale. Use the Circle of Fifths when you want to see how keys relate, for example which keys are closest for a key change, or which three major chords (I, IV and V) sit together in a key.
- How do I transpose a song for a singer?
- Work out how many semitones higher or lower the song should be (trying the melody at a few different pitches helps), then paste the chords or the whole chord sheet into the Transposition Tool and set that number. Lyrics stay put and only the chords change, spelled to suit the new key. Guitarists moving up a few semitones can often keep the original shapes and use a capo instead; the tool tells you which fret.
- Why might my instrument sound slightly off from the Note Frequency Reference?
- The reference uses equal temperament with A above middle C at 440 Hz, the modern standard. Many orchestras tune slightly higher, at 442 or 443 Hz, and Baroque groups use 415 Hz, so pick your tuning from the list. Pianos are also usually “stretch tuned”, with the top notes a little sharp and the bottom notes a little flat, so a real piano won't match the table exactly at the extremes.