UtilibyWritten by the Utiliby editorial team · Last updated October 13, 2026 · Rules and formulas reviewed October 2026
What this free song key finder does
The key of a song is the set of notes and the home note that the music is built around. Knowing it lets a guitarist pick the right chords, a singer decide whether a song fits their voice, and a DJ mix two tracks so they sound harmonious instead of clashing. Apps that detect keys are often paid. This free online song key finder works out the key of a file in your browser, so there is no upload and no sign-up.
It shows the key, a confidence level, the Camelot and Open Key codes used by DJs, the relative major or minor, the notes of the scale, the basic chords in the key, and the key of each section. A chart shows how strongly each of the twelve notes is present, and a button plays the scale so you can check the result by ear.
How to find the key of a song in three steps
- Drop the file. MP3, WAV, M4A, FLAC and the audio of video files work.
- Wait a few seconds. The tool listens to the notes and compares them with the patterns of the 24 keys.
- Read the result. Look at the key, the confidence and the runner-up. Press Play the scale and hum or play along to confirm that the notes feel right.
How the detection works
The audio is split into short overlapping frames. For each frame, the tool finds the strongest frequency peaks between about 110 Hz and 2 kHz, where most melody and harmony lives, and assigns each peak to one of the twelve pitch classes: C, C sharp, D and so on. Adding these up over the whole song produces a chroma profile, which is the bar chart in the results. It shows how much of the music is spent on each note regardless of octave.
The profile is then compared with typical profiles of major and minor keys. These come from listening experiments by Krumhansl and Kessler, and from the corpus-based profiles of Temperley. The tool averages the two sets, and the best-matching of the 24 keys wins. Before any of this, it estimates the tuning of the recording, so a song tuned slightly sharp is not mistaken for the next key up.
Camelot wheel and Open Key codes
DJs often use the Camelot wheel to plan mixes. Each of the 24 keys has a code from 1 to 12 with a letter. B is major and A is minor. The table lists all 24.
| Camelot | Key | Camelot | Key |
|---|---|---|---|
| 1B | B major | 1A | Ab minor |
| 2B | F# major | 2A | Eb minor |
| 3B | Db major | 3A | Bb minor |
| 4B | Ab major | 4A | F minor |
| 5B | Eb major | 5A | C minor |
| 6B | Bb major | 6A | G minor |
| 7B | F major | 7A | D minor |
| 8B | C major | 8A | A minor |
| 9B | G major | 9A | E minor |
| 10B | D major | 10A | B minor |
| 11B | A major | 11A | F# minor |
| 12B | E major | 12A | C# minor |
Open Key uses the same idea with different labels. Major keys are numbered with a d and minor keys with an m, starting with C major as 1d and A minor as 1m.
Mixing in key
Two tracks sound smooth together when their keys share most of their notes. On the Camelot wheel, that means the same code, the same number with the other letter (the relative major or minor), or one step up or down on the same letter, which is a fifth away. Moving a key up by seven steps raises the energy, and shifting a track by a semitone or two with a pitch control can bring it into a compatible key.
Mixing in key is a guide, not a rule. Rhythm and energy matter just as much, and clashing keys can be a deliberate effect. Use the BPM Detector to match the tempo, and the Audio Speed and Pitch Changer to nudge the key.
Relative keys, modes and ambiguity
Every major key shares its notes with a minor key three semitones below it. C major and A minor both use only the white notes of a piano. When the harmony does not make the home note clear, detection can fall on either. The tool lists the runner-up for this reason. Songs in modes such as Dorian or Mixolydian, which are common in rock, folk and funk, use the notes of a major key but center on another note, and they can match the relative major or the nearest minor.
To decide between two answers, find the note the melody and the bass keep returning to and ending on. That is the home note. Play it, then play the scale, and see which sounds like it belongs.
Songs that change key
Many songs move up a tone or a semitone for the last chorus, and some classical and jazz pieces travel through several keys. The tool analyzes sections of about thirty seconds and shows the best key for each. If the sections agree, the song is in a steady key. If they differ, treat the headline key as an average and read the table to see where the changes happen.
Getting the best result
- Use the full song or a section with harmony. A drum intro gives little to work with.
- Use the studio version rather than a live bootleg with a noisy crowd.
- If the confidence is low, analyze a section with clear chords, such as a verse or a chorus.
- Check the result by ear with the scale player.
- Remember that a transposed, sped-up or slowed-down version changes the key, and the result reflects the file you load.
Common uses
- DJs: plan harmonic mixes with Camelot codes.
- Guitarists and pianists: pick chords and a capo position.
- Singers: check whether a song fits their range.
- Producers: match samples and loops to a project key.
- Songwriters: find the key of a demo recording.
- Music students: check an analysis exercise.
Troubleshooting
- The result is the relative key: look at the runner-up and play the scale to decide.
- The confidence is low: use a section with clear chords, or a longer file.
- Nothing was found: the file may be speech, drums or silence.
- The key differs from another app: different tools use different profiles. Trust your ear and check both answers.
- The file will not load: convert it to MP3 or WAV.
Privacy and how it works
Your browser decodes the file into samples, and the page analyzes them in memory with JavaScript. Nothing is uploaded, stored or logged. Closing the tab clears the audio from memory.
Frequently asked questions
How do I find the key of a song?
Drop the song into the box above. The tool listens to the notes in the audio, compares them with the typical note patterns of the 24 major and minor keys, and shows the best match with Camelot and Open Key codes, scale notes and chords. Press Play the scale to check it by ear.
How accurate is the key detection?
For songs with a clear harmony it is often right, and it shows the runner-up and a confidence level so you can judge. It can be wrong on music that changes key, uses modes or unusual scales, is mostly percussion, or has a sparse harmony. Treat it as a strong starting point.
Why does it sometimes pick the relative minor or major?
Relative keys, such as C major and A minor, use exactly the same seven notes, so the music can match either. The tool lists the relative key and tells you when it was the runner-up. To decide, listen to which note feels like home, and check where the melody and bass line settle.
What is the Camelot wheel?
The Camelot wheel is a way of naming the 24 keys with a number from 1 to 12 and a letter. A means minor and B means major. Keys with the same number or neighboring numbers on the same letter sound harmonious when mixed, which makes it popular with DJs.
What is Open Key notation?
Open Key is another numbering of the same wheel, used by some DJ software. Major keys end in d and minor keys end in m. The tool shows both so that you can use whichever your software prefers.
Which keys mix well together?
The same key, the relative major or minor, and the keys one step up or down the wheel on the same letter. The tool lists these for the key it detects.
Can it tell if a song is in a minor or major key?
Yes. It compares the notes with both major and minor patterns. If a song is very ambiguous, the confidence will be low and the relative key will be listed.
What if the song changes key?
The tool also analyzes sections of about thirty seconds and lists the key of each. If the key changes, you will see it in the table. The headline result is the best average over the analyzed audio.
Does it handle songs that are tuned a little flat or sharp?
Yes. It estimates how far the recording is from A = 440 Hz and corrects for it before choosing the notes. This helps with old recordings and sped-up or slowed-down tracks.
How much of the song does it analyze?
Up to four minutes from the middle of the file, which is enough for a reliable result. Shorter files are analyzed in full.
Is my file uploaded to a server?
No. The file is decoded and analyzed on your device, and nothing is sent anywhere.
Can I find the key of a vocal or an instrument recording?
Yes, if the recording has pitched notes over time. A single sustained note gives the note but not a clear major or minor key. A melody or a few chords works best.
Why does the tool show scale notes and chords?
They help you play along. The scale notes are the seven notes of the key. The chords are the seven basic chords built on each of those notes, with Roman numerals, which many songs draw from.
Does it work on drums or spoken audio?
No. Percussion and speech do not have clear musical notes, so there is nothing for key detection to use.
What does the match number r mean?
It is a correlation between the notes in the music and the typical pattern of a key. Values near 1 mean a very close match. Real music usually scores between 0.5 and 0.9. The gap to the runner-up matters more than the number itself.
Can I use the key to transpose a song?
Yes. Once you know the key, you can work out how many semitones to move it. Use the Audio Speed and Pitch Changer to shift the key without changing the tempo.
What can I print or save from the page?
Print / save summary prints the detected key, codes and details, and Copy result copies them as text.
Sources and further reading
- Krumhansl, C. L. and Kessler, E. J. (1982). Tracing the dynamic changes in perceived tonal organization in a spatial representation of musical keys. Psychological Review, 89(4), 334-368.
- Temperley, D. (2001). The Cognition of Basic Musical Structures, MIT Press, for the key-finding profiles.
- Müller, M. (2015). Fundamentals of Music Processing, Springer, chapter on chroma features and key detection.
- MDN Web Docs, Web Audio API, for how browsers decode audio into samples.
Sources were consulted in October 2026. Standards and rules can change, so always check the official page for your situation.