Is my audio uploaded?

No. Reading and analysing both happen inside your browser, and the audio is never sent anywhere. Nothing is stored on a server, and closing the page clears it from memory.

How accurate are the key and BPM?

They are estimates. Pop and dance material with a clear pulse is usually right; classical, ambient and heavily modulating music often is not. A confidence level is shown with each result — when it is low, trust your ears instead.

Why does a 320 kbps file still sound bad?

Bitrate says how much space was used to store the audio, not how good the audio was to begin with. Something encoded at 128 kbps and then converted to 320 kbps or WAV does not get its top end back. The bandwidth figure and the frequency plot show that history.

What happened to the waveform and the export?

They were removed. This page now does one thing: tell you what a file is. Converting and exporting belong to the file converter, and splitting a track into parts belongs to the stem separator.

Which formats are supported?

MP3, WAV, M4A, AAC, FLAC, OGG, Opus and AIFF, plus the audio track of MP4, MOV, WebM and other video. What actually opens also depends on the browser — Safari on iPhone cannot read OGG, Opus, WebM or WMA.

Does it work on long files?

Usually, but the audio is expanded into memory in full, so anything over an hour may fail on a phone. Accuracy does not depend on length: key and BPM are read from 120 seconds in the middle either way.

The scale the track centres on. Camelot is the same thing in DJ notation (8A, 5B…), where neighbouring numbers — and A↔B on one number — tend to mix cleanly.

Beats per minute. Where half and double are both defensible you get "87 or 174" — treat both as valid readings.

Distance from A=440. Tape and vinyl transfers, A=442 orchestras and A=432 tracks sit 20–50 cents off, and the key is read against this rather than assuming concert pitch.

File size over duration. 128 kbps is light for MP3, 320 kbps is high quality, and lossless runs past 1000. A high bitrate does not guarantee the source was good quality.

Measurements per second — 44.1 kHz for CD, 48 kHz for video — and the highest frequency storable is half of it. This is the file’s own rate, not your playback device’s.

The highest frequency carrying sound. A sharp drop here means an encoder cut it off: roughly 16 kHz for 128 kbps, around 20 kHz for 320 kbps.

The loudest instant and the average level, both under a 0 dB ceiling. A peak of exactly 0 dB suggests clipping; a small gap between the two means a loudness-compressed mix.

Stereo (two) or mono (one). A stereo file can still hold identical audio on both sides, leaving anything that works from the difference with nothing to use.

Key · BPM · quality

Find out what a file is

Input

Drag & drop the file you want to check

or click to choose

MP3, WAV, M4A, AAC, FLAC, OGG, Opus, AIFF and more — plus the audio of MP4, MOV, WebM and other video

Result

Nothing here yet

Key, BPM, bitrate and bandwidth, detected automatically — and an explanation of what each number actually means.

What this tool tells you

Key and BPM: Useful groundwork for a cover or a remix. The Camelot code is shown too, so it drops straight into a DJ workflow.
Compression history: If the frequency plot stops short of the top, the audio has already been through a low-bitrate encoder — even if the file extension is .wav.
A check before you start: Is it clipped? Is it really stereo? Is it the length you expected? All of it can be confirmed before you start editing or separating.

How to use

Choose the file to inspect
Drag and drop an audio file — MP3, WAV, M4A, FLAC and the like — or a video, or click to choose one.
Read the results
Analysis starts as soon as the file has loaded: key, BPM, length, average bitrate, sample rate, channels, peak and bandwidth. Key and BPM are estimates, so each is shown with a confidence beside it.
Look at the frequency plot
The plot under the results runs frequency across and level up. A sharp drop at the top end means everything above it was lost to compression. What each figure means is set out below, under how to read the numbers.

How to read the numbers

Key / Camelot: The scale the track centres on. Camelot is the same thing in DJ notation (8A, 5B…), where neighbouring numbers — and A↔B on one number — tend to mix cleanly.
BPM: Beats per minute. Where half and double are both defensible you get "87 or 174" — treat both as valid readings.
Tuning: Distance from A=440. Tape and vinyl transfers, A=442 orchestras and A=432 tracks sit 20–50 cents off, and the key is read against this rather than assuming concert pitch.
Average bitrate: File size over duration. 128 kbps is light for MP3, 320 kbps is high quality, and lossless runs past 1000. A high bitrate does not guarantee the source was good quality.
Sample rate: Measurements per second — 44.1 kHz for CD, 48 kHz for video — and the highest frequency storable is half of it. This is the file’s own rate, not your playback device’s.
Bandwidth: The highest frequency carrying sound. A sharp drop here means an encoder cut it off: roughly 16 kHz for 128 kbps, around 20 kHz for 320 kbps.
Peak / RMS: The loudest instant and the average level, both under a 0 dB ceiling. A peak of exactly 0 dB suggests clipping; a small gap between the two means a loudness-compressed mix.
Channels: Stereo (two) or mono (one). A stereo file can still hold identical audio on both sides, leaving anything that works from the difference with nothing to use.

Frequently asked questions

Is my audio uploaded?: No. Reading and analysing both happen inside your browser, and the audio is never sent anywhere. Nothing is stored on a server, and closing the page clears it from memory.
How accurate are the key and BPM?: They are estimates. Pop and dance material with a clear pulse is usually right; classical, ambient and heavily modulating music often is not. A confidence level is shown with each result — when it is low, trust your ears instead.
Why does a 320 kbps file still sound bad?: Bitrate says how much space was used to store the audio, not how good the audio was to begin with. Something encoded at 128 kbps and then converted to 320 kbps or WAV does not get its top end back. The bandwidth figure and the frequency plot show that history.
What happened to the waveform and the export?: They were removed. This page now does one thing: tell you what a file is. Converting and exporting belong to the file converter, and splitting a track into parts belongs to the stem separator.
Which formats are supported?: MP3, WAV, M4A, AAC, FLAC, OGG, Opus and AIFF, plus the audio track of MP4, MOV, WebM and other video. What actually opens also depends on the browser — Safari on iPhone cannot read OGG, Opus, WebM or WMA.
Does it work on long files?: Usually, but the audio is expanded into memory in full, so anything over an hour may fail on a phone. Accuracy does not depend on length: key and BPM are read from 120 seconds in the middle either way.

Input

Result

What this tool tells you

How to use

Choose the file to inspect

Read the results

Look at the frequency plot

How to read the numbers

Frequently asked questions