Key Detector
Identify the musical key of any chord progression. Understand which key your chords belong to and why.
Detect the key in Chord Player
Add your chords in Chord Player and use the Roman Numeral view to see which key your progression belongs to.
Open Chord Player →How to find the key of a chord progression
The key of a chord progression is determined by the tonal center — the chord that feels like "home." Here are the most reliable methods:
Check for a V7 chord
A dominant 7th chord (e.g. G7) almost always resolves to its I chord (Cmaj7). If you have G7 → C, the key is C major.
Find all the diatonic chords
List the chords and find the major scale that contains all of them. For C, G, Am, F — all four fit perfectly into C major (I, V, vi, IV).
Listen for the resting chord
The chord where the progression feels resolved or complete is usually the I (tonic). Play the progression and notice where it "wants to land."
Check relative minor
C major and A minor share the same chords. A progression starting on Am and ending on Am is likely in A minor. Starting on C and ending on C is likely C major.
Examples — hear the key
All chords are diatonic to C major. The I chord (C) is the tonal center.
Starts on Am — feels like A minor. Same notes, different tonal center.
ii–V–I in C. The G7 resolves strongly to Cmaj7, confirming C as the key.