Is my audio uploaded anywhere?

No, nothing is uploaded. The file is decoded by your own browser in the page you are looking at, the analysis runs on the samples in memory, and nothing is sent to a server at any point. There is no account and no queue, and closing the tab is all it takes to be rid of the file.

Why does it show half-time and double-time instead of one number?

Because a steady pulse correlates with itself just as well at half its rate and at twice it, which is why one detector says 140 and another says 70 about the same track. The tool leans towards tempos near 120, the way a listener does, then shows you the half and the double with the scores they actually earned, so you can see the choice rather than inherit it.

What does the confidence figure mean?

It is how far the winning tempo stands above the best tempo that is not one of its own octaves. A half-time reading never counts against it, because that is not a disagreement about the beat. Strong means one tempo scored well clear of every unrelated rival, weak means more than one unrelated tempo fits and tapping along is the fastest way to settle it.

The number is wrong. Can I correct it?

Yes, two ways. Press Tap on each beat and the tempo those taps describe goes straight into the Your tempo box, which is exact arithmetic on your taps rather than an estimate. Or type the number yourself, between 40 and 220 BPM. Either one replaces the estimate on screen, and the beat markers are re-placed around the tempo you gave.

How much of the file does it listen to?

Up to 60 seconds, starting at the beginning unless you type a start and an end. When your section is longer than that the readout says so rather than trimming it quietly. A tempo is measured from a stretch of steady pulse, so a chorus is usually a better section to point it at than a fade-in.

What are the limits, and what will it refuse?

Files up to 50 MB, in any format your browser can already play, and sections of at least 4 seconds. Silence, an empty file, a format the browser cannot decode, a section too short to hold the slowest tempo twice, and a stretch where nothing starts at all, a held note or room noise, all come back as a message naming what happened and what to change, never as a number that was guessed.

Does it detect the key as well?

No. This measures tempo only: an onset envelope, an autocorrelation and the candidates that came out of it. Nothing here reads a key, a time signature or anything written in the session file the track came from.

Can I detect BPM from an MP3, WAV or OGG file?

Yes, when your browser can decode that file. Choose a local MP3, WAV, M4A, OGG or FLAC and select a section with a steady beat. Codec support varies, so an unreadable file gets a message instead of a tempo; exporting a WAV is an alternative. Detection is an estimate, and half-time or double-time can fit the same music.

Can I use the BPM detector on Android, iPhone or Mac?

Use the page in a browser that supports local audio decoding. Choose a file on your device, or press Tap once per beat to count the tempo manually. No native app or installation is required for this browser workflow. The format your device can decode determines which audio files open.

Does it detect live microphone audio or a song link?

No. Automatic detection takes a local audio file, not a microphone stream, Spotify or YouTube link. You can listen to music and tap its beat manually, but that is a tapped tempo rather than live automatic detection. The page also does not read MIDI tempo events or detect a musical key.

BPM detector

Choose a local audio file to estimate its tempo without uploading it. The detector searches from 40 to 220 BPM and shows confidence plus half-time and double-time candidates. Tap along or type a tempo to adjust the result and beat markers. Files can be up to 50 MB, with four to sixty seconds analysed at a time. The core tool is free and needs no account.

Open an audio file

· or drop a file anywhere on the stage. It is decoded here and never sent anywhere.

Never uploadedNo accountUp to 50 MB40 to 220 BPM

Estimate

not measured yet

Confidence

not measured yet

Candidates

not measured yet

Analysed

nothing yet

Start

End

Your tempo

Ready. Choose an audio file, or drop one on the stage.

Tempowhat the tool concluded, and from how much audio
No tempo measured yet.
Half and doublethe same pulse counted the other way, with its score
Open a file to see the half-time and double-time candidates.
Beat markersseconds from the start of the section analysed
Open a file to place the beats.

Why there is a list and not one number. A steady pulse matches itself just as well at half its rate and at twice it, so an algorithm that answers 140 and one that answers 70 are usually reading the same song. This tool scores the strongest pulse between 40 and 220 BPM, leans towards tempos near 120 the way a listener does, and then shows the half and the double with their own scores instead of hiding the choice it made. If it picked the wrong one, tap along with the Tap button or type the number in the Your tempo box: both replace the estimate, and the beat markers move with it.

What the readings mean

Confidence is one specific thing: how far the winning tempo stands above the best tempo that is not one of its own octaves. A half-time reading never counts against it, because that is not a disagreement about the beat. An unrelated tempo scoring alongside the winner does, and that is the file worth tapping along to. The beat markers are placed by finding the phase that lines up best with the onsets, so they are as steady as the performance is: a track played to a click lands on them, and a band that drifts will not.

Accuracy. An estimate, not a reading from the session file. It scores the strongest steady pulse and lists the half-time and double-time candidates beside it, because those are genuinely ambiguous in most music. Tap along or type the number to correct it. Nothing is uploaded: the file is decoded in this tab and dropped when you leave the page, and at most 60 seconds of it are analysed at a time.

Common questions

Is my audio uploaded anywhere?: No, nothing is uploaded. The file is decoded by your own browser in the page you are looking at, the analysis runs on the samples in memory, and nothing is sent to a server at any point. There is no account and no queue, and closing the tab is all it takes to be rid of the file.
Why does it show half-time and double-time instead of one number?: Because a steady pulse correlates with itself just as well at half its rate and at twice it, which is why one detector says 140 and another says 70 about the same track. The tool leans towards tempos near 120, the way a listener does, then shows you the half and the double with the scores they actually earned, so you can see the choice rather than inherit it.
What does the confidence figure mean?: It is how far the winning tempo stands above the best tempo that is not one of its own octaves. A half-time reading never counts against it, because that is not a disagreement about the beat. Strong means one tempo scored well clear of every unrelated rival, weak means more than one unrelated tempo fits and tapping along is the fastest way to settle it.
The number is wrong. Can I correct it?: Yes, two ways. Press Tap on each beat and the tempo those taps describe goes straight into the Your tempo box, which is exact arithmetic on your taps rather than an estimate. Or type the number yourself, between 40 and 220 BPM. Either one replaces the estimate on screen, and the beat markers are re-placed around the tempo you gave.
How much of the file does it listen to?: Up to 60 seconds, starting at the beginning unless you type a start and an end. When your section is longer than that the readout says so rather than trimming it quietly. A tempo is measured from a stretch of steady pulse, so a chorus is usually a better section to point it at than a fade-in.
What are the limits, and what will it refuse?: Files up to 50 MB, in any format your browser can already play, and sections of at least 4 seconds. Silence, an empty file, a format the browser cannot decode, a section too short to hold the slowest tempo twice, and a stretch where nothing starts at all, a held note or room noise, all come back as a message naming what happened and what to change, never as a number that was guessed.
Does it detect the key as well?: No. This measures tempo only: an onset envelope, an autocorrelation and the candidates that came out of it. Nothing here reads a key, a time signature or anything written in the session file the track came from.
Can I detect BPM from an MP3, WAV or OGG file?: Yes, when your browser can decode that file. Choose a local MP3, WAV, M4A, OGG or FLAC and select a section with a steady beat. Codec support varies, so an unreadable file gets a message instead of a tempo; exporting a WAV is an alternative. Detection is an estimate, and half-time or double-time can fit the same music.
Can I use the BPM detector on Android, iPhone or Mac?: Use the page in a browser that supports local audio decoding. Choose a file on your device, or press Tap once per beat to count the tempo manually. No native app or installation is required for this browser workflow. The format your device can decode determines which audio files open.
Does it detect live microphone audio or a song link?: No. Automatic detection takes a local audio file, not a microphone stream, Spotify or YouTube link. You can listen to music and tap its beat manually, but that is a tapped tempo rather than live automatic detection. The page also does not read MIDI tempo events or detect a musical key.

An estimate, not a reading from the session file. It scores the strongest steady pulse and lists the half-time and double-time candidates beside it, because those are genuinely ambiguous in most music. Tap along or type the number to correct it.