Key finder · chords to key
Key Finder: What Key Are These Chords In?
Type the chords of a song in order. The finder ranks all 24 major and minor keys, names every chord’s function, and shows the seven chords that belong to the key.
Most likely key
C major
100% of the chords belong to this key
| Chord | In C major |
|---|---|
| C | I |
| G | V |
| Am | vi |
| F | IV |
All seven chords in C major
- I C
- ii Dm
- iii Em
- IV F
- V G
- vi Am
- vii° Bdim
Also possible
- A minor — 100% fit: III · VII · i · VI
- F major — 75% fit: V · – · iii · I
How the key finder works
Each major key has seven chords built from its scale: in C major they are C, Dm, Em, F, G, Am and B diminished. The finder checks your chords against all twelve major keys and all twelve minor keys, counting how many belong — a dominant 7th on the fifth degree (G7 in C) counts extra, because it points so clearly at home.
Minor keys are checked with both their natural chords and the raised-seventh chords minor-key music uses all the time: A minor accepts Em and E or E7, and G♯ diminished. That is how Am–Dm–E7–Am comes out as A minor rather than C major.
Finally, progressions usually start or end at home, so a key gets a bonus when its home chord is first or last. That splits a major key from its relative minor, which share all seven chords.
Not sure what a chord is called?
If you know the shape but not the name, put it into the chord finder first, then bring the names back here. To practice the chords of the key you found, open the scales tool in that key.
Frequently asked questions
How do I find the key of a song from its chords?
List the chords in order and check which key contains all of them. Every major key has seven chords — three major (I, IV, V), three minor (ii, iii, vi) and one diminished (vii°) — so a progression that uses only those seven belongs to that key. If two keys fit, the one whose home chord starts or ends the progression is usually right.
Why does it say a major key and its relative minor both fit?
Because they share exactly the same seven chords: C major and A minor both use C, Dm, Em, F, G, Am and Bdim. What separates them is where the music comes to rest. A progression that ends on C is in C major; one that ends on Am, or uses E or E7 (the minor key's raised V), is in A minor.
What do the Roman numerals mean?
They number each chord by the step of the scale it is built on. Upper case is a major chord, lower case a minor chord, ° diminished. So in C major, G is V and Am is vi — and C–G–Am–F is I–V–vi–IV in any key, which is why the same song can be played in any key with the same numerals.
What if a chord is outside the key?
Plenty of songs borrow chords from outside the key — a B♭ or A♭ in a C major rock song, or an E7 in C major leading to Am. The finder marks those chords as outside the key and still picks the key the rest of the progression fits best.