Chords → key, scale and numerals
Song Key Finder
Type or tap the chords of a song and the key finder tells you which key it is in, what each chord's job is (I, IV, V…), which chords are borrowed, the scale to solo with, and the other chords that would fit.
How the key finder works
Every major key contains seven chords — I, ii, iii, IV, V, vi and vii° — and every minor key has its own seven. The key finder checks your chords against all 24 keys, gives extra weight to the chord the song starts and ends on and to V → I cadences, and allows for borrowed chords (like ♭VII or iv in a major key), which rock and pop use all the time. Chords marked with * are borrowed; dashed ones are outside the key.
What to do with the result
- Soloing: use the scale shown (or its pentatonic version) — open it on the neck with Show the scale.
- Writing: the "other chords that fit" are safe choices for a new section or a bridge.
- Singing: if the key is too high or low, move it with the chord transposer or a capo.
Questions
How do I find the key of a song from its chords?
Look for the key that contains the most of its chords, then check which chord feels like home — usually the first and last chord. This tool does both automatically.
Why do two keys get similar scores?
Every major key shares its chords with its relative minor (C major and A minor, for example). The difference is which chord the song resolves to.
What is a borrowed chord?
A chord taken from the parallel key — for example ♭VII or iv in a major key. They add colour and are very common in rock and pop.