Find the key from the chords you know
Got a few chords from a song and want to know the key, or which other chords will sound right with them? Enter them above. The finder checks all 30 major and minor keys and shows you where each chord sits as a Roman numeral.
Reading the results
- Green-edged chords belong to the key's scale.
- Purple chords use the raised seventh of the harmonic minor scale, such as E major in A minor.
- Red chords are outside the key. If one is a major or dominant chord a fifth above a key chord, it's flagged as a secondary dominant, e.g. V/V.
Why Roman numerals?
Numerals describe a chord's function instead of its name. A I–V–vi–IV progression sounds the same in any key, so learning it once lets you play it everywhere. Uppercase means major, lowercase means minor, and ° means diminished.
Tips for better answers
- Enter chords in the order they're played. The first and last chords are strong clues to the tonic.
- Include all the chords you know, even unusual ones. A single outsider is useful information.
- Use the share link to send your analysis to a bandmate.
Want to build the skill instead of looking it up? Try the Which Key drill, or see every chord in every key in the chord chart.
Frequently asked questions
How does the key finder work?
It builds every major and minor key, checks which of your chords are made only from notes in that key, and ranks the keys by how many chords fit. Ties are broken by whether the first and last chords are the tonic and whether the V chord is present.
Why does it list more than one key?
Chords often belong to several keys at once. C, F and G all appear in C major and also A minor. Adding more chords narrows the answer.
What does a red chord mean?
It is outside the key. That is normal in real music: it may be a secondary dominant such as D7 in C major, a borrowed chord, or a sign the song modulates. The tool labels secondary dominants for you.
Which chord symbols can I type?
Major (C), minor (Cm, C-), 7ths (C7, Cmaj7, CΔ, Cm7), diminished (Cdim, C°), half-diminished (Cm7b5, Cø), augmented (Caug, C+), sus chords, 6ths, add9, 9ths and slash chords like C/E.