How to Find the Key of a Song: 3 Easy Methods
By Solfa Theory · Published: 20 October 2026 · Updated: 20 October 2026
Quick answer: how do you find the key of a song?
If you have the sheet music, read the key signature. If you do not, write down the song's chords and find the one major key that contains all of them. Then confirm by ear: the key is the note and chord the song feels finished on.
New to keys? Start with our music theory for beginners guide, then come back.
Knowing the key of a song tells you which notes and chords will sound right with it. It is the first thing a band asks before a jam, and the first thing you need to know to play along, write a solo or change the key to suit your voice. There are three reliable ways to find it, and the best answer comes from using two of them together.
What a key is
A key is the scale a piece of music is built around, together with the note that acts as home. A song in G major mostly uses the notes G A B C D E F♯ and feels settled when it arrives on G. That home note, and the chord built on it, is called the tonic. Finding the key means finding the scale and the tonic.
Method 1: Read the key signature
On sheet music, the sharps or flats at the start of each line are the key signature. Count them and use the chart below. Each signature fits two keys: a major key and its relative minor, which share the same notes.
| Key signature | Major key | Relative minor |
|---|---|---|
| No sharps or flats | C major | A minor |
| 1 sharp | G major | E minor |
| 2 sharps | D major | B minor |
| 3 sharps | A major | F♯ minor |
| 4 sharps | E major | C♯ minor |
| 5 sharps | B major | G♯ minor |
| 1 flat | F major | D minor |
| 2 flats | B♭ major | G minor |
| 3 flats | E♭ major | C minor |
| 4 flats | A♭ major | F minor |
| 5 flats | D♭ major | B♭ minor |
If you would rather not memorise the chart, use this shortcut. With sharps, look at the last sharp in the signature: it is the seventh note of the major key, so the key is a half step above it. Two sharps, F♯ and C♯, end on C♯, and a half step above is D, so the key is D major. With flats, the second-to-last flat names the major key. Three flats, B♭ E♭ A♭, give E♭ major. One flat is the exception, and that key is F major.
Then decide major or minor. Look at the first and last notes or chords of the piece, and listen. For a full picture of how the keys connect, see the circle of fifths guide.
Method 2: Work it out from the chords
If you only have a chord chart, or you have figured out the chords by ear, this method is the most reliable. Each major key has seven chords that naturally belong to it. Write down the chords the song uses and find the key that contains them all.
| Key | I | ii | iii | IV | V | vi | vii° |
|---|---|---|---|---|---|---|---|
| C major | C | Dm | Em | F | G | Am | Bdim |
| G major | G | Am | Bm | C | D | Em | F♯dim |
| D major | D | Em | F♯m | G | A | Bm | C♯dim |
| F major | F | Gm | Am | B♭ | C | Dm | Edim |
Example: a song uses the chords G, Em, C and D. All four appear in the G major row, but C major has no D major chord (it has Dm), so the key is G major. This is the I, vi, IV, V pattern, and you can read more about it in seven common chord progressions.
Sometimes the chords fit two keys. If a song uses Am, F, C and G, they all fit C major and also A minor, because those keys share their notes. To decide, ask which chord feels like home. If the song starts and ends on C and sounds bright, it is C major. If it settles on Am and sounds darker, it is A minor. The Chords & Scales tool helps you check which chords belong to a key.
Method 3: Find it by ear
No sheet music and no chords? You can still find the key with your ears, an instrument and a few minutes.
- Listen for the home note. Play the song and pay attention to the end, or to any place where the music feels finished. Hum or tap the note that feels like it is resting.
- Find that note on an instrument. Try notes on a piano or the Piano tool until one matches the resting note. That note is very likely the tonic.
- Test major or minor. Play a major chord on that note, then a minor chord. Whichever sounds right against the song tells you whether the key is major or minor.
- Check with the chords. If you can, confirm with Method 2. When the by-ear answer and the chord answer agree, you are done.
This gets quicker with practice. If it feels hard, how to train your ear and identify chords by ear will help.
Things that can trip you up
- Relative major and minor. They share notes, so the key signature alone cannot tell them apart. Use the home chord.
- Key changes. A song can move to a new key part way through. Check each section.
- Borrowed chords. A chord that is not in the key does not mean the key is different. Songs often borrow a chord for colour. Look at the majority of the chords.
- Modes. Some songs use scales such as Dorian that do not sound major or minor. See modes explained.
- Apps and key finders. They can give a quick estimate, but can be wrong on songs that change key or use unusual chords. Treat them as a second opinion.
Frequently asked questions
How can I find the key of a song?
Use the key signature if you have the sheet music, or write down the chords and find the one key whose scale contains all of them. Then check by ear: the key is the note and chord the song feels finished on. Two of these methods agreeing is a reliable answer.
How do you identify a key?
Look at three things: the sharps or flats in the key signature, the chords the song uses, and the chord it starts and ends on. The key is the major or minor scale that fits all three. The tonic, the home chord, is usually where the song settles.
What is the trick for figuring out key signatures?
For sharps, the last sharp in the signature is the seventh note of the major key, so the key is a half step above it. For flats, the second-to-last flat names the major key. One flat is the exception: that key is F major.
How do I know if a song is major or minor?
Every key signature fits one major key and its relative minor. Listen to where the song feels at home. If the home chord is major and the mood is bright, it is major. If it settles on a minor chord and sounds darker, it is the relative minor.
Can a song have more than one key?
Yes. Many songs change key part way through, often up a whole step or a half step near the end. Find the key of each section separately, and treat a key finder app as a guide for the main key rather than a final answer.
Where to go next
Once you can name a song's key, you can learn its scale and chords, and start improvising over it. Our major vs minor scales guide is the next step, and the full beginner path is in music theory for beginners.