Audio BPM Detector
Estimate the beats per minute (tempo) of any audio file by analyzing onset patterns. Useful for DJs, producers, dancers, and anyone who needs to know a song's tempo. Files are analyzed entirely in your browser.
About Audio BPM Detector
Estimate the beats per minute (tempo) of any audio file by analyzing onset patterns. Useful for DJs, producers, dancers, and anyone who needs to know a song's tempo. Files are analyzed entirely in your browser.
All analysis happens entirely inside your browser using the Web Audio API. Your audio file never leaves your device — there is no upload, no account, no tracking. Closing the tab fully erases the file from memory.
Browser-based audio analysis trades a little speed for total privacy. Server tools can crunch big lossless files faster on dedicated CPUs, but they require uploading your file. Here, decoding and analysis run on the same hardware you're holding.
Related tools
About Audio BPM Detector
Audio BPM Detector runs the audio editing and conversion job locally inside your browser. Estimate the beats per minute (tempo) of any audio file by analyzing onset patterns. Useful for DJs, producers, dancers, and anyone who needs to know a song's tempo. Files are analyzed entirely in your browser. The work happens on your machine, the result is generated on your machine, and the page exposes the controls you need to drive it without burying them in menus.
Technically, the work is done by standard browser APIs, loaded as part of the page. Inputs in MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, and WMA format are recognised automatically and validated before the engine begins processing. Files up to 200 MB are supported per run; that ceiling keeps browser memory usage stable on a wide range of devices.
Audio BPM Detector is a static page plus a client-side engine. The browser does the work; there is no separate backend in the loop for the actual processing. That architecture is why the tool starts immediately, why it does not depend on the load on a remote service, and why running multiple jobs in a row does not slow it down.
If you fit any of these descriptions, Audio BPM Detector should slot cleanly into your workflow: streamers cleaning microphone tracks; language learners reviewing speech; students preparing oral submissions. The tool keeps the controls focused on what matters for each of these use cases.
Audio BPM Detector is shaped for the gap between "I'll do it by hand" and "I'll script it." When the job is small enough that automating it would take longer than doing it, but annoying enough to want a focused tool — that is the situation this page is built for.
A practical note on limits: Audio BPM Detector accepts inputs up to 200 MB per run, and the tool processes one input at a time to keep memory usage predictable. If you ever bump into the ceiling, the cause is the size of the input.
As a workflow component, Audio BPM Detector is the part you reach for when a single, well-defined audio editing and conversion step needs to happen. It performs that step and returns a standard file you can carry into the next part of your pipeline.
Some notes on the design of Audio BPM Detector. The page is intentionally narrow: one input, the controls relevant to the task, and one output. Adding unrelated features would make the common case slower for the majority of users, so the surface is held to what people actually use.
The output handed back by Audio BPM Detector is `{name}-edited.{ext}`. If you would prefer to keep the result in the browser instead of downloading it, you can copy it from the result panel and paste it directly into another tab — useful when the next tool in your workflow expects pasted text rather than a file.
Some background on the design choices behind Audio BPM Detector: every option you see on the page is there because a real workflow needs it, and every option that is not shown has been deliberately omitted to keep the common case fast. The bias is toward minimal-but-complete.
If you also use a command-line tool for audio bpm detector, Audio BPM Detector is a convenient alternative for the times you are on a different machine or helping someone who is not comfortable in a terminal. The output is a standard file in the format documented above.
If you want to get the most out of Audio BPM Detector, three small habits help. Drag-and-drop is faster than the file picker once you get used to it. The keyboard shortcut for downloading the result is whatever your browser uses for "save link as," because the result is a normal download. And if you are working on a sensitive file, processing in an Incognito or Private window is a good extra layer — it leaves no trace in browser history when the tab closes.
If the result is not what you expected, the most common causes are easy to check. Confirm the input is under the 200 MB ceiling — files just above the cap fail silently because the engine refuses to allocate the buffer. Confirm the input is one of the supported formats. And if the page itself feels slow, try closing other heavy tabs to free up memory; the engine runs in your browser, so it competes for the same resources as everything else open.
Open the workspace above to start using Audio BPM Detector. The engine loads on the first interaction so the page itself stays light, and once the tool is warm it processes subsequent jobs quickly. The moment the page is interactive, the tool is ready to do real work on your file.
How it works
- 1Reach the Audio BPM Detector page in your browser to begin.
- 2Drop a MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, and WMA file onto the upload area, or click to pick one from your device.
- 3Adjust the options to match what you need. Sensible defaults cover the most common case, so you can usually skip this step.
- 4Trigger processing. standard browser APIs reads your input, applies the transformation, and writes the result back into the page.
- 5Save the output (`{name}-edited.{ext}`) when it is ready.
- 6Re-run with different settings as often as you want. Each run produces a fresh output and the original file on disk is never modified.
Common use cases
- Boost a quiet interview recording to a normal listening level using Audio BPM Detector.
- Compress a music demo small enough to share over messaging.
- Stitch several voice notes into a single playable file.
- Convert a band's rough mix into a format mastering software accepts.
- Re-encode a lossless track into a portable format for the gym.
- Split a long mixtape into individual track files.
- Extract the audio from a video so it can be edited separately.
- Convert a voice memo into a format your editor can open.
- Record a quick test tone to verify a microphone setup.
- Trim the cough out of the first ten seconds of a podcast take.
FAQ
How is BPM detected?
The audio is decoded to PCM and analyzed for onsets — the moments where loud transients (kick drums, snares, percussion) occur. The intervals between onsets are clustered to find the most common tempo. The algorithm is similar to those used by Beatport, Mixed in Key, and other DJ tools.
How accurate is the result?
For songs with clear, steady percussion (most pop, rock, EDM, hip-hop): very accurate, typically within 1 BPM. For acoustic music with no percussion or with heavily syncopated rhythms: less reliable, may report half or double the actual tempo. For songs with tempo changes, the result is the average tempo.
Why does it sometimes report half or double the real BPM?
BPM detection is fundamentally ambiguous — a song at 120 BPM has equally valid onsets at 60 BPM (the half-time feel) and 240 BPM (the double-time feel). Algorithms have to guess which level you mean. If the result feels off, multiply or divide by 2 and use the value that feels right.
When is BPM detection useful?
DJs need it for beatmatching tracks. Producers need it for setting their DAW tempo to a sample. Dancers and instructors use it to plan choreography. Fitness instructors match music to workout intensity. Editors sync video cuts to musical beats. Filmmakers pick a song's actual tempo for crossfades.
Why is in-browser BPM detection slower than apps?
Detection requires decoding the entire audio file (or a representative sample) and running the analysis. Apps like Mixed in Key are faster because they're native and use multiple threads. WebAssembly's single-thread limit makes ours slower, but the algorithm and accuracy are comparable.
How big a file can I analyze?
Up to 200MB. The analyzer scans the first few minutes for the tempo (additional analysis adds little accuracy), so even long files complete relatively quickly.
Why is in-browser audio processing slower than online tools?
Server-side tools use multi-threaded native FFmpeg running on dedicated CPUs with fast disks and parallel pipelines. Our engine is FFmpeg compiled to WebAssembly, which runs single-threaded inside your browser tab and has no access to native hardware acceleration. That makes browser-based jobs typically 3–8× slower than a server. The trade-off is total privacy: your audio file is never uploaded, never logged, and never stored — closing the tab erases everything from memory immediately. For most clips up to a few minutes the wait is small, and for sensitive recordings (voice memos, drafts, confidential meetings) the privacy gain is well worth it.
Is my audio uploaded?
No. Everything runs entirely inside your browser tab using FFmpeg compiled to WebAssembly. The file is read into local memory only, processed in the same tab, and the result is offered as a direct download. Nothing is transmitted to any server, no account is required, no analytics are tied to your file, and closing the tab discards every byte from memory.
How big a file can I process?
The file picker accepts audio inputs up to about 1 GB, which is well above what mainstream "free tier" online converters allow. The real ceiling is your device — everything runs inside your browser tab, which shares memory with the rest of the page. Most podcasts, songs, and voice memos sit comfortably under that limit even on a phone. If a very large lossless WAV or FLAC ever fails, trim it first or transcode to MP3 / Opus to bring the size down before re-running the tool.
Which audio formats are supported?
MP3, WAV, OGG (Vorbis and Opus), FLAC, M4A (AAC), AAC, Opus, AIFF, and WMA all decode reliably via FFmpeg WASM. Output formats depend on the specific tool — most editing tools default to MP3 (universal) or WAV (lossless) but expose a format picker so you can pick the one that fits your downstream player or DAW.
Which browsers are supported?
Recent Chrome, Edge, Firefox, Safari, and other Chromium-based browsers all work. The tool relies on WebAssembly and SharedArrayBuffer, which require the page to be served over HTTPS with the right cross-origin headers — this site is configured correctly by default. On phones the same code runs but is slower than on a desktop because mobile CPUs are weaker.
Is there a watermark, sign-up wall, or usage cap?
No. The tool is completely free, requires no account, attaches no watermark, applies no usage caps, and shows no popup ads on your output. Because the work happens on your own device, there is no per-user quota for us to enforce — your hardware and browser memory are the only limits. The download is the file you would get from running FFmpeg locally, nothing more, nothing less.
Does Audio BPM Detector reduce quality of the result?
Audio BPM Detector is built to preserve quality wherever the underlying audio format allows it. Operations that are mathematically lossless (e.g. structural transformations, lossless re-encoding) round-trip with no perceptible change. Operations that involve a lossy codec inevitably introduce small artefacts at the byte level, but the defaults aim at the sweet spot where output looks or sounds the same to a normal viewer or listener while still being meaningfully smaller or faster than the input.
Is there a desktop version of Audio BPM Detector?
No installation is needed. Audio BPM Detector runs as a normal web page, with no browser extension, no native helper, and no separate desktop client to download. That is partly a privacy choice — extensions can request broad permissions, while a regular page is sandboxed by default — and partly a convenience one: you can use Audio BPM Detector on any computer you have temporary access to without leaving anything installed on it.
Is Audio BPM Detector mobile-friendly?
Audio BPM Detector runs in any modern mobile browser — Safari, Chrome, Firefox and the in-app browsers in most messaging apps all support the underlying APIs. Performance depends on the device: a recent phone handles typical inputs nearly as fast as a laptop, while older devices may take a few seconds longer near the 200 MB ceiling. The interface lays out cleanly on small screens, so you do not need to pinch-zoom to see the controls.
How do I run Audio BPM Detector over a folder of files?
Audio BPM Detector processes one input at a time by design — it keeps memory usage predictable on lower-end devices and makes results easier to verify. To handle a folder, run the tool once per file; the page stays loaded between runs and remembers your last-used settings, so the second run is essentially instant.
How long does Audio BPM Detector take to process a file?
Most jobs finish in seconds. Speed scales with input size and with how many CPU cycles your browser tab has available — the engine runs in your browser, so it shares resources with whatever else you have open. For inputs near the 200 MB ceiling, expect anywhere from a few seconds to roughly a minute on a typical laptop. Closing other heavy tabs noticeably speeds things up.
Is Audio BPM Detector licensed for business use?
Audio BPM Detector can be used for personal and commercial work alike — there is no separate "business" licence to purchase. The output you generate is yours to use however you want, including in client deliverables, internal documents, or commercial products. Favtoo's only ask is fair, individual use; the tool is not designed to be embedded as a backend service or wrapped behind an API for resale.
Will Audio BPM Detector keep working if my Wi-Fi drops mid-task?
Once the page is loaded, Audio BPM Detector can complete jobs without an active internet connection — the engine is bundled with the page, so there is no per-job network call. The initial page load does require a connection (to fetch the static assets), but after that you can disconnect entirely and the tool will still work. This is a side-effect of the local-first architecture, not a deliberate "offline mode" feature.