Free Audio Key Detector
VCM Audio Key + Scale Detector
Find out what key your audio is in. Major or minor, with confidence scores and modulation detection.
Free to useNo account requiredFiles not stored
You found a beat. You found a sample. You have no clue what key it's in.
This tool tells you in seconds. Upload any audio file and get the key, scale (major or minor), and a confidence score. If the track modulates, you'll see where the key changes happen.
No more guessing. No more playing random notes on your keyboard to figure it out. Just upload, detect, and get back to making music.
Prep Stack Workflow
Key detection is step one. Combine it with these tools for a complete audio prep workflow:
1
Key Detector
Find the key and scale
You are here
2
BPM Finder
Detect the tempo
Go
3
Audio to MIDI
Transcribe to notes
Go
How It Works
1
Upload
Drop your audio file
2
Analyze
Extract chroma features
3
Match
Compare to key profiles
4
Results
Get key + confidence
Features
Key + Scale Detection
Identifies both the tonic (A, B, C, etc.) and mode (major/minor)
Modulation Detection
Finds key changes with timestamps
Confidence Scores
Know how certain the detection is
Honest Limitations
- Complex harmony can confuse detection. Jazz, atonal music, and frequent chord changes may show ambiguous results.
- Modulations are best-effort. The windowed analysis catches obvious key changes but may miss subtle ones.
- Works best on tonal audio. Drums, noise, and sound effects have no key—expect low confidence.
- Short clips reduce confidence. Longer excerpts (30+ seconds) give more reliable results.
- Enharmonic equivalents. C# and Db are the same pitch; we pick one notation.
Frequently Asked Questions
How do I find the key of a song?
Upload your audio file (MP3, WAV, FLAC, etc.) and click "Detect Key". Our algorithm analyzes the harmonic content using chroma features and compares it against standard key profiles to identify the most likely key and scale.
Can this detect major vs minor?
Yes. The detector distinguishes between major and minor keys by comparing your audio against both Krumhansl-Schmuckler major and minor key profiles. It will tell you whether the track is in a major key (like C major) or minor key (like A minor).
How accurate is key detection?
Accuracy depends on the audio content. Clean, tonal music (piano, guitar, vocals) typically achieves 80-90% accuracy. Complex harmony, key changes, or percussive content can reduce accuracy. We show a confidence score so you know how certain the detection is.
Why does it show low confidence?
Low confidence usually means: (1) the audio is mostly percussive with little tonal content, (2) the harmony is ambiguous or chromatic, (3) there are frequent key changes, or (4) the recording is noisy. Try using a cleaner excerpt or isolating the melodic elements.
Can it detect key changes (modulations)?
Yes. The tool analyzes your audio in 8-second windows and identifies segments where the key changes. If your track modulates from A minor to C major, you'll see both keys listed with their timestamps.
What audio works best?
Tonal audio with clear harmonic content works best: piano, guitar, synths, vocals, orchestral music. Drum loops, noise, and heavily distorted audio give unreliable results. Longer excerpts (30+ seconds) also help improve accuracy.
Does it work on vocals-only?
Yes, isolated vocals work well for key detection since they contain clear pitch information. Acapellas are great inputs. However, heavily processed vocals with lots of reverb or autotune artifacts may reduce accuracy.
Does it work on full mixes?
Yes, full mixes work, but accuracy depends on the mix. If the harmonic elements (chords, bass, melody) are prominent, detection is reliable. Very dense or complex mixes may show lower confidence.
What file types are supported?
We support MP3, WAV, M4A, FLAC, and OGG audio files. Maximum file size is 25MB and maximum duration is 10 minutes. Files are converted internally before analysis.
Do you store my audio?
Your audio is processed in a temporary directory and deleted immediately after analysis. The analysis results (JSON) are stored for 2 hours to allow downloads, then automatically deleted. We don't keep copies of your music.
How do I use this with BPM Finder?
The Key Detector and BPM Finder work together in our "Prep Stack" workflow. First detect the key, then find the BPM—you'll have both pieces of information needed to match samples, create remixes, or produce in the same key and tempo.
How do I use this with Audio to MIDI?
Once you know the key, use our Audio to MIDI converter to transcribe the melodic content. Knowing the key helps you interpret the MIDI correctly and make adjustments in your DAW.
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