How to find the key of a song from notes, chords and resolution

1. Choose a short, stable section

Use the end of a chorus, a repeated hook or another passage that clearly resolves. Avoid an intro with effects, a bridge that modulates or a vocal run full of passing notes. Write down five to eight clear melody notes and the bass or chord at the phrase ending.

2. Separate structural notes from decoration

Passing notes, slides and blue notes can briefly sit outside the basic scale. Give more weight to long notes, phrase endings and notes that coincide with a strong bass or chord change.

3. Compare relative major and minor

If the notes fit C major, they also fit A natural minor. Ask which chord sounds like home.

4. Test a real progression

The chords Am–F–C–G belong to the same note collection. If the hook repeatedly settles on A and the strongest ending is E7–Am, A minor is the better label. If the melody resolves to C and the cadence is G–C, C major is more convincing. The chord list alone is not enough; musical emphasis decides.

5. Verify in a repeatable workflow

1. Write down the clearest melody notes and the final bass note.
2. Identify candidate tonic and dominant chords.
3. Play each candidate triad in the tool and read the recognised chord plus its related major/minor context.
4. Play the suspected tonic under the phrase ending.
5. Check the real bass movement and final cadence.
6. Transpose only after the tonal centre feels stable.

If two candidates remain plausible, report uncertainty instead of inventing precision.

Common mistakes

• Calling the first chord the key.
• Analysing three passing notes.
• Ignoring a modulation between verse and chorus.
• Calling every white-note melody C major.
• Trying to distinguish relative keys from note names alone.