Song Key Finder Calculator
Determine the likely key of a song by entering the notes present in the melody or chords.
About this calculator
This tool identifies a song's likely key by pattern-matching against the two most common scale shapes in Western tonal music: the major scale and the natural minor scale, each defined by a fixed set of semitone intervals from its root note. You enter up to seven notes present in the melody or chord progression, and the calculator checks how many of those notes fall inside each of the 12 possible major scales and each of the 12 possible minor scales, reporting whichever key scores the highest match in each mode along with a confidence percentage. This is a genuinely useful starting point for ear-training or quick key identification, but it has one real, structural limit worth understanding: a major scale and its relative natural minor share all seven of their notes (C major and A minor, for instance, use exactly the same seven pitch classes) -- they differ only in which note functions as the tonal center, not in note content.
Because this calculator only counts which pitch classes are present, it cannot distinguish a key from its relative minor by note content alone; that is exactly why it reports a Likely Major Key and a Likely Minor Key side by side rather than picking one. Telling the two apart for real requires listening for which note the melody resolves to and treats as "home," which is outside what a note-presence count can measure. More distinct notes entered still narrows down the field of unrelated keys the melody clearly isn't in.
Inputs
Results
Likely Major Key
C major
Likely Minor Key
A minor
How to Use This Calculator
- Choose Note 1, Note 2, and Note 3 from the note dropdowns, or leave them at "(none)" if you have fewer notes to enter.
- Set Note 4, Note 5, and Note 6.
- Choose Note 7 as needed.
- Review the Likely Major Key and Likely Minor Key results — the calculator can't tell a key apart from its relative minor by note content alone, so both are shown.
- Use Confidence, Matched Notes, and Unmatched Notes to gauge how well your note set fits the winning scale.
What each input means
- Note 1
- A note present in the song. Choose "(none)" if you have fewer than seven notes to enter.
- Note 2
- Another note present in the song, or "(none)" if unused.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersNote 1 (0-11, -1=unused) = 0, Note 2 = 2, Note 3 = 4, Note 4 = 5 = 7 input(s) provided
- Calculate Likely Major Key0 = 0
- Calculate Likely Minor Key9 = 9
- Calculate ConfidenceConfidence100 = 100
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does this calculator show a Likely Major Key and a Likely Minor Key instead of just one answer?
Because a major scale and its relative natural minor scale share all seven of their notes -- C major and A minor, for example, use exactly the same seven pitch classes and differ only in which note the ear hears as "home." This calculator counts which pitch classes are present, so for any given note set it cannot tell a key apart from its relative minor; showing both candidates side by side is the honest result rather than an arbitrary guess between the two.
Do unused note slots affect the result?
No -- any note slot left at -1 (its "unused" sentinel value) is excluded from the analysis entirely and has zero effect on the Likely Major Key, Likely Minor Key, or Confidence outputs. You can enter as few as one or two real notes and leave the rest at -1 without changing how the calculator scores the notes you did provide.
What does the Confidence percentage actually measure?
It's the share of your entered notes that fall inside the best-matching scale's seven notes -- if you enter five distinct notes and four of them belong to the top-scoring key's scale, Confidence reads 80%. It measures internal consistency with the winning scale, not certainty that the winning scale is musically correct; a small note set can still hit 100% confidence while matching multiple candidate keys equally well.
Should I enter notes from the melody, the chords, or both?
Either works, and combining both generally gives a more reliable result. The calculator only cares which of the 12 pitch classes appear somewhere in what you enter, not whether they came from a melodic line or a chord voicing, so notes drawn from both the tune and its harmony give the widest, most representative sample of the song's actual note content.
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