How to Find the Key and Scale of a Song on Guitar

You want to solo over a song, or write a part that fits, and the first question is always the same: what scale is this in? You don’t need perfect pitch to answer it. You need a method, and about five minutes. Here’s the one that works, with three worked examples and a scale finder you can use right on this page.

Key vs. scale: a quick definition

A song’s key is its home note plus the set of notes it mostly uses. A song in A minor rests on A and mostly uses the notes A B C D E F G. The scale is that set of notes in order. So finding the key and finding the scale are almost the same job: find the home note, then find the notes around it.

Step 1: Find the home note

Play the song (or the riff) and hum the note that feels like the end of a sentence: the one where the music could stop and feel finished. That is the tonic, the root of the key.

Three clues help:

• The last chord of the song or of a chorus is usually the tonic chord.
• The first chord very often is too.
• The bass keeps returning to the tonic, especially at the start of sections.

Find that note on your low E or A string by sliding until it matches what you’re humming. (If the fretboard is still fuzzy, the fretboard notes guide will help.)

Step 2: Is it major or minor?

Play the tonic note’s major chord and then its minor chord over the song. One of them will sound right and the other will clash. If the home chord is major, start with the major scale; if it’s minor, start with the natural minor.

Step 3: Collect the notes

Write down every different note you can find in the chords or the melody. You don’t need them all (four or five is plenty), and octaves don’t matter.

If you have the chords, this is easy: spell each chord and pool the notes. Am is A C E; F is F A C; and so on.

Step 4: Match the notes to a scale

Now find the scales that contain every note you collected. Try it here: tap in your notes and the list narrows to the scales that fit:

You’ll usually get several matches that share the same notes but start on different roots: C major and A minor, for example. That’s where your answer from Step 1 decides it: pick the one whose root is the home note you hummed.

Step 5: Check it against the chords

Every scale produces a family of chords. If the song’s chords all belong to that family, you’ve confirmed the key. If one chord doesn’t fit, it tells you something interesting: usually that the song borrows from a related scale. The “chords in this scale” section on each scale page (for example, chords in A minor) makes this check quick.

Worked example 1: Am – F – C – G

Home note: the progression starts and ends on Am, and A feels like home. Minor.

Notes: Am (A C E) + F (F A C) + C (C E G) + G (G B D) = A B C D E F G

Match: those seven notes are C major or A minor (and the other modes of C). The home note is A, so the scale is A minor. For a solo, the A minor pentatonic is the safe, classic choice.

Worked example 2: E – D – A – E

Home note: E. The E chord is major.

Notes: E (E G♯ B) + D (D F♯ A) + A (A C♯ E) = E F♯ G♯ A B C♯ D

Match: try E major first: E F♯ G♯ A B C♯ D♯. But the song has a D natural, not D♯. Those notes are A major starting on E: that’s E Mixolydian. The giveaway is the D chord: a major chord one whole step below the tonic (♭VII) is the classic Mixolydian sign.

Worked example 3: Am – Dm – E

Home note: A, minor.

Notes: Am (A C E) + Dm (D F A) + E (E G♯ B) = A B C D E F G♯

Match: that’s natural minor with a G♯ instead of G: the A harmonic minor scale. A minor key with a major V chord (E instead of Em) almost always means harmonic minor over that chord.

Tell-tale chords and the scales they point to

You hear…	It suggests…
A major chord on the ♭VII in a major key (G–F)	Mixolydian
A major IV chord in a minor key (Dm–G)	Dorian
A major V chord in a minor key (Am–E)	Harmonic minor
A chord a half step above the tonic (Em–F)	Phrygian
A major II chord in a major key (F–G over F)	Lydian
Dominant 7th chords on I, IV and V	Blues scale / minor pentatonic

When nothing fits

• One stray note? It may be a passing note, a bend or a “blue” note. Remove it and try again.
• The key changes. Choruses and bridges often move to a new key. Analyse each section on its own.
• Borrowed chords. Rock and pop love to borrow a chord from the parallel key (a ♭VI or ♭VII in a major song). The rest of the song will still point to one scale.
• It’s an exotic scale. If the notes really don’t match a common scale, the full library in Guitar Scale Finder (1,870 scales, including Byzantine, Hungarian minor, Hirajoshi and bebop scales) will usually find it.

Or let your phone listen

The Guitar Scale Finder app can also help you find scales to play over a song with Magic Listen. Tap the filter button, then Magic Listen. Hold your phone up to a speaker or play a riff. It hears the notes, works out the key and opens its scale, or filters the scale list if it hears an unusual set of notes. It listens until it is sure, taking longer to tell major from relative minor; the relative is one tap away on the result. Listening needs iOS 27 and the audio stays on your device. The method above helps you check which scale feels like home.

Frequently asked questions

How do I find the scale of a song quickly? Find the home note by ear, collect four or five notes from the chords or melody, then look for the scale on that root that contains them all. A scale finder does the matching for you.

How can I tell if a song is in a major or minor key? Play the tonic’s major and minor chords along with the song. The one that fits tells you whether the key is major or minor.

Why do several scales match the same notes? Relative scales share notes: C major and A minor are identical sets. The home note decides which name is right.

Can I find a scale from just three notes? Yes, but you’ll get more matches. Three notes like A, C and E fit dozens of scales; adding a fourth and fifth narrows it down fast.