How to Find the Key of a Chord Progression
Updated July 2026 · by Loopin
If you know the chords but not the key, you’re most of the way there — the chords themselves give it away. Here’s how to read the key straight out of a progression.
Find the chord that feels like home
Most progressions revolve around one chord that feels settled — the one the music keeps returning to and usually ends on. That ‘home’ chord is your strongest clue to the key. Play the progression in a loop and notice where it feels like it could comfortably stop; that resting point is almost always the tonic.
If the home chord is major, you’re likely in a major key named after it; if it’s minor, a minor key. A progression that loops C–G–Am–F and lands on C is in C major. The same four chords reordered to start and end on Am point to A minor instead — same notes, different home, which is the relative minor relationship in action.
Match the chords to a scale
Every key has a set of chords that belong to it — its diatonic chords. In a major key, the pattern is major, minor, minor, major, major, minor, diminished as you move up the scale. So C major naturally contains C, Dm, Em, F, G, Am and B diminished. If your progression’s chords all fit inside one of these families, you’ve found the key.
Try it as a process of elimination. List your chords, then ask which single key contains all of them. If a progression uses G, C, D and Em, the only major key holding all four is G major. This is exactly how the chords in our circle of fifths writeup line up — neighbouring keys share most chords, so the odd chord out usually tells you which side of the line you’re on.
When it isn’t obvious
Some progressions borrow chords from outside the key for colour, or modulate partway through, which can muddy the picture. A lone surprising chord — a major chord where you’d expect minor, say — is often a borrowed chord rather than a sign you’ve got the wrong key. Trust the home chord and the chords that repeat most.
Modal progressions throw another wrench in, because they centre on a note without the usual pull of a major or minor key. If a progression feels like it never quite resolves the way you expect, you may be in a mode — our guide to musical modes explains how those work and why they can fool a quick key check.
Confirm it in seconds
If you have a recording of the progression — even a rough phone demo of you playing it — you can skip the analysis. Drop it into the free key & BPM finder and it returns the key, like G major, in seconds, along with the Camelot code if you’re matching it to other parts.
It’s the fastest sanity check: work out the key from the chords, then confirm with the finder before you build a topline or add samples on top. Detection is an estimate on ambiguous or modulating material, so use it alongside your ear rather than instead of it. For the broader method, see how to find the key of a song.
Frequently asked questions
How do I find the key from a chord progression?
Find the chord the progression keeps resolving to and usually ends on — that's the home chord and almost always the key. Then check that the other chords belong to that key's diatonic family. If they all fit one key, that's it.
What if my progression has a chord that doesn't fit the key?
It's often a borrowed chord added for colour, not a sign you've got the wrong key. Trust the home chord and the chords that repeat most. If the progression never resolves as expected, you may be in a musical mode rather than a standard major or minor key.
Can I find the key from chords automatically?
If you have a recording of the progression, drop it into the free Loopin key & BPM finder and it reports the key in seconds — useful for confirming the key you worked out by hand.