Plan a Harmonic DJ Set
Check BPM and key before a set and line up tracks whose keys are related.
For example
- Harmonic mixing
- Set prep
What the Key and BPM Finder Tells You
The key and BPM finder reads an audio file in your browser and returns four things: the tempo as a whole number of beats per minute between 80 and 160, the key as one of 24 major or minor keys, the seven notes of that key, and three closely related keys. Tempo comes from onset detection and autocorrelation across the track; the key comes from comparing the song's pitch-class profile with major and minor templates. When either reading is weak, the result is marked as low confidence instead of being passed off as certain.
Three Readings From the Key and BPM Finder
One file in, one tempo, one key and its neighbors out.
Tempo in BPM
Tempo is rounded to a whole number and always reported between 80 and 160 BPM, so a ballad felt at 70 shows as 140 and a track at 170 shows as 85.
What you see
80-160 BPM
Every reading lands here
Whole Numbers
Rounded, not decimals
Onset Based
Reads the beat pattern
Why Check With This Key and BPM Finder
Numbers you can act on before you mix.
01Private
Analysis on Your Device
The file is decoded and analyzed in the browser and is never uploaded.
02Keys
All 24 Keys
Major and minor for every root, with the scale notes listed.
03Tempo
80 to 160 BPM
Tempo as a whole number, always between 80 and 160, so half-time and double-time songs show the same BPM.
04Mixing
Related Keys Listed
Three neighboring keys that tend to blend, ready for harmonic mixing.
05Honest
Weak Readings Flagged
A low-confidence label appears instead of a guess presented as fact.
06Formats
Seven Formats, 80 MB
MP3, WAV, OGG, FLAC, AAC, M4A and WebM, free with no credits.
Who Uses a Key and BPM Finder
Six jobs where the key and BPM finder saves guesswork.
Match a Sample to a Project
Read a sample's key and tempo before dropping it into a project.
For example
- Sample key
- Loop tempo
Pick a Singing Key
Find a song's key, see its scale notes, and decide whether to sing it higher or lower.
For example
- Cover key
- Warm-ups
Train Your Ear
Check the scale notes in the results against what you hear. It's good ear-training practice.
For example
- Ear training
- Scale study
Check a Mashup Pair
Run two songs through the key and BPM finder. If the tempos are within 12% and the keys are no more than 5 semitones apart, the mashup maker will accept the pair.
For example
- Pair check
- Swap test
Cut Video on the Beat
Use the BPM to place cuts on the beat in an edit.
For example
- Beat cuts
- Montage timing
Use the Key and BPM Finder in Three Steps
Files can be up to 80 MB and 5 minutes long on a computer, or 2 minutes on a phone.
- 1Step
Add an Audio File
Drop in a song or clip you have on your device.
- 2Step
Run the Analysis
Press the button and wait while the file is decoded and analyzed.
- 3Step
Read and Compare
Note the BPM, key, scale notes and related keys, then check the next song.
Key and BPM Finder Questions
How it reads songs, what the numbers mean, and how to pair tracks.
How does the key and BPM finder work out a song's key?
The key and BPM finder turns the audio into a profile of how much each of the 12 pitch classes is used, then compares it with major and minor key templates and picks the closest match. Tempo comes from finding note onsets and the most regular gap between them.
Why is my BPM reading half or double what I expected?
Tempo has octave ambiguity: a song felt at 70 BPM can also be counted at 140. The key and BPM finder always reports a tempo between 80 and 160, so a 70 BPM song shows as 140 and a 174 BPM song as 87. The mashup maker compares tempos at normal, half and double speed, so this does not block a pair.
How do I use the results to pick a mashup pair?
Run both songs through the key and BPM finder, then divide the higher BPM by the lower one. If the result is 1.12 or less, the mashup maker accepts the pair, counting half and double time. For keys, a relative minor counts as its major. The vocal can be shifted up to 5 semitones, so a pair is only turned down when the keys are 6 semitones apart.
Which keys are related to the one I got?
Three keys are closely related, and the key and BPM finder lists them under your result. For C major they are A minor, G major and F major; for A minor they are C major, E minor and D minor. Songs in these keys share most of their notes and tend to blend in a mix.
Why does the key and BPM finder flag some results as uncertain?
A low-confidence flag means the beat or the key was not clear enough, which happens with free tempo, heavy drums over little harmony, ambient tracks or short clips. Try a longer section or the full song, and treat the flagged value as a hint.
What happens with songs that change key or tempo midway?
The key and BPM finder gives one key and one BPM for the whole file, so a song that changes key or tempo partway shows the dominant reading. To check a section, trim it into its own file first.
Which files can the key and BPM finder analyze?
MP3, WAV, OGG, FLAC, AAC, M4A and WebM files up to 80 MB, up to 5 minutes long on a computer or 2 minutes on a phone. It reads files on your device only; YouTube or streaming links are not supported.
Is the key and BPM finder free, and does my file leave my device?
The key and BPM finder is free and uses no credits. Analysis happens inside your browser, so the audio is not uploaded or stored on a server.
Other Tools to Use With Your Results
Change a track once you know its key and tempo.
