BPM and key finder: analyse a song online

What the analysis gives you

• Tempo in beats per minute, to one decimal place (for example 123.9 BPM).
• Key and mode: the tonic and whether the track is major or minor (for example A minor).
• Genre, from a catalogue of 400 styles, with a confidence level for each.
• Mood and instrumentation, plus whether the track is vocal or instrumental.
• Integrated loudness in LUFS, with a note on whether the master is ready for streaming.

Because the values are computed from your file, the tool works on demos, stems, bounces and anything else that has never been released, which database-driven BPM lookups cannot do.

How to analyse a track

1. Drop your file in the studio. No account is needed for the first analysis.
2. Wait about 20 seconds while the track is decoded and analysed.
3. Read the report: tempo and key, then genre, mood and instruments. Export it to CSV, JSON or PDF if you need to keep it.

Working on an EP or a DJ set? Batch mode takes up to 10 files at once and lines up the tempo and key of every track side by side, with the average tempo of the set.

How tempo and key are measured

Both values are measured directly from the audio signal:

• Tempo comes from beat tracking: the algorithm locates the beats across the track and derives the tempo from the spacing between them.
• Key comes from the harmonic content: the energy of each of the twelve pitch classes is measured over the track and compared with the typical profiles of major and minor keys.

Both are computed over the whole track, up to 7 minutes, and reported as a single value. Genre, mood, instruments and loudness are assessed on a 90-second window taken from the body of the track.

Reading the BPM: when to double or halve it

Tempo detection is reliable on music with a steady pulse, and it has well-known blind spots that apply to every BPM detector:

• Half-time and double-time. A drum and bass track at 174 BPM may be reported at 87, a trap beat at 70 may come out at 140. Both readings are musically valid: if the number feels twice too fast or too slow, double or halve it.
• Tempo changes. A track that speeds up, slows down or switches tempo gets one overall value, which may match none of its sections exactly.
• Free or live timing. Rubato, live drums without a click and ambient pieces have no stable pulse to measure, so the result is an approximation.

Reading the key: relatives, modulations and Camelot codes

Key detection reports the most likely key for the track as a whole. Two things to keep in mind:

• Relative keys share the same notes. C major and A minor use the same seven notes, so a detector can pick one for the other. For mixing or sampling purposes, the two are compatible anyway.
• Modulations are averaged out. A song that changes key for its last chorus gets the key that dominates overall.

The report gives the key as a note and a mode. If you mix harmonically and think in Camelot codes, use this conversion table: tracks mix well when they share a code, sit one number apart (8A with 7A or 9A) or swap letter on the same number (8A with 8B).

What BPM and key are used for

• DJs: beatmatching, and harmonic mixing so that two tracks do not clash when they overlap.
• Producers: finding samples and loops that fit, building a remix or a mashup, sending a collaborator the right session settings.
• Artists and managers: filling in release metadata, answering a sync brief that asks for a tempo range, describing a track accurately when pitching it.
• Labels and publishers: tagging a catalogue consistently so that it can be searched by tempo, key, mood and genre.

More than a BPM counter

Tag-per-Track was built for A&R work, so tempo and key are only the first lines of the report. The same analysis also returns an A&R score from 0 to 100, a check for AI-generated music and, if you link an artist, their live Spotify audience. If you are about to send your music to labels, it shows you roughly what a label using demo screening software will see.

Being upfront about price: the first analysis is free, then an analysis costs one credit, about €0.15, with packs of 33 credits for €5 or 100 credits for €15 that never expire. If all you need is one number for one song, the free analysis covers it.

Frequently asked questions

Is the BPM and key finder free?

Your first analysis is free, with no card and no account. After that, each analysis costs one credit: €5 for 33 credits or €15 for 100 credits, and credits never expire.

Which audio files can I analyse?

WAV, MP3, FLAC, AIFF, M4A and AAC files, up to 50 MB and 7 minutes per track. You upload the audio file itself: links to streaming platforms are not supported.

How accurate is the BPM detection?

It is reliable on tracks with a steady beat. The usual sources of error are half-time or double-time readings (87 instead of 174 BPM, for example), tempo changes within the track, and music without a stable pulse. If the value looks twice too high or too low, double or halve it.

How accurate is the key detection?

It reports the most likely key for the whole track. The most common confusion is between a key and its relative (C major and A minor share the same notes), and a song that modulates is given the key that dominates. Checking the result against an instrument takes a few seconds and is worth doing before a release.

Does it give Camelot codes for DJ mixing?

The report gives the key as a note and a mode, such as A minor. The conversion table on this page gives the matching Camelot code, 8A in that example.

What happens to the track I upload?

The file is stored temporarily for the analysis and deleted as soon as the report is generated. Tag-per-Track does not keep your audio and never uses it to train AI models. Tempo and key are computed on our own servers; two other steps rely on external providers: the AI check, run on a 12-second excerpt, and lyrics transcription, which is optional and sends the full track.