Find the note that feels like “home” or the most stable ending
Check the last chord or note of the song
Identify the chord that appears most often
Listen for the chord that sounds resolved and complete
Look for the scale the melody mostly uses
Match the song’s notes to a major or minor scale
Check the key signature if you have sheet music
Use a piano or guitar to test notes and chords against the song
Try singing the tonic note and see if it fits naturally
Use a key detection app or software if needed
Compare the song’s chords to common progressions in major or minor keys
Confirm whether the song sounds brighter or darker to help distinguish major from minor