Type a chord progression — the analyzer detects the key, Roman numerals, compatible scales and mood. Works with triads, 7ths through 13ths, altered dominants, half-diminished and slash chords — Am, Cmaj7, F#m, Bb, G7, Dm7, C/E, Gm7b5, D13 and more.
Enter your chords separated by spaces. The analyzer maps each chord to its constituent notes, then scores all 12 major and 12 minor keys by how many chord tones they contain. The key with the highest score wins — with a secondary candidate shown when the result is ambiguous. Minor keys also count the raised seventh (the leading tone of harmonic minor), and when two keys fit equally well, the one whose tonic chord opens or closes the progression wins.
Roman numeral notation (I, ii, iii, IV, V, vi, vii°) shows each chord's function within the detected key. This helps you understand why progressions create certain emotional feelings — the V→I resolution, the bittersweet vi chord, or the tension of a diminished vii°.
Want to learn more about how harmony and chord progressions work in practice? Visit Cloud Atelier Studio for guides on music theory, composition, and ear training. Need to build a progression instead of analyze one? Use the Chord Progression Generator, move an existing one to another key with the Chord Transposer, or hear how each chord in a key sounds with the Scale & Chord Finder. Progression sounding right and ready to record? Before you post it, run the mix through the Pre-Master Checker for a LUFS and mono compatibility check built for Instagram, TikTok and Spotify.
How do I find what key a chord progression is in?
Type the chords separated by spaces and press Analyze. The tool breaks each chord into its
notes, then scores all 24 major and minor keys by how many of those notes they contain. The
highest-scoring key is the most likely one, shown with a confidence percentage and a second
candidate when the result is close.
What key are these chords in — can the analyzer tell me?
Yes. That is what the detected key card shows. Paste chords like C G Am F and it reports C
major, with A minor as the relative alternative.
What do the Roman numerals mean?
Each numeral shows a chord's position and quality in the detected key: uppercase for major
(I, IV, V), lowercase for minor (ii, iii, vi), a circle for diminished (vii°), ø for
half-diminished, and the chord's own suffix after it — I6, IVadd9, V7, Imaj7, Vsus4. This is
how you see the function of every chord.
Which chord types does it support?
Triads, sixths, sevenths through thirteenths, sus2 and sus4, add9, augmented, diminished,
half-diminished, altered dominants such as 7b9 and 7#5, and slash chords like C/E. Chord
symbols are case-sensitive, so Cmaj7 and Cm7 are never confused.