BPM Detector

Overview

Drop a track and get its tempo to one decimal place. The beat grid is drawn on the waveform, so you can see and hear whether the lines sit on the drums instead of trusting a number. When two tempos fit equally well, like 174 and its half-time 87, you get both. The same pass also shows the key, loudness and peak, and your file stays on your computer.

Beat-match a setGet exact tempos for your tracks so you know what mixes with what.
Set a project tempoFind the BPM of a reference track and start your session at the same tempo.
Check a tagged BPMLibrary tags are often wrong or rounded, so measure the file itself.

Guides

01 How to find the key and tempo of a track

Set

Audio Tools 17

Neighbours

01 Audio Transcriber 02 Generate AI Music 03 Audio Converter 04 DJ Booth 05 Extract Audio from Video 06 Audio HLS Stream Generator

Specification

Command: audio.bpm_detector
Set: Audio
Input: MIXED
Output: —
Max file: 1GB
Batch: single file

MPEG WAV FLAC MP4 OGG OPUS AAC WEBM

Runtime

Engine: ffmpeg-wasm 0.12
Threads: — workers
Isolated: —
WebGPU: —
Memory: —

Transport 0 B

Your file is opened, worked on and saved inside this tab. This tool has no upload step, so your file has nowhere else to go.

Keys

Search: ⌘K
Panels: ⌘1 · ⌘2
Full width: F
All keys: ⌘/

How it works

Drop a track

Any audio file, or a video with sound, decoded on your device.

Read the tempo

The BPM shows first, with the beat grid drawn over the waveform below.

Check the grid

Press play; if the lines land on the drums, the tempo is right.

Frequently asked

How accurate is the BPM?

On music with a clear beat it's accurate to a few thousandths of a beat, and the grid stays in line across the whole track. The harder part is the level you mean, say 87 or 174. When both fit equally well, the tool shows both and lets you pick.

Why does it sometimes show half or double the tempo I expected?

Because both describe the same recording. Nothing in the audio says whether a listener would tap along at the slower or the faster rate. When the two are close, confidence drops and the other reading is shown next to the main one.

Is my music uploaded?

No. The file is decoded and analysed in your browser with Web Audio, in a background worker. Nothing leaves your device.

What formats can I use?

MP3, WAV, FLAC, M4A/AAC, OGG and Opus, plus the audio from video files. MP4, MOV and WebM are read by your browser directly. For MKV, AVI, WMV, FLV and others, FFmpeg pulls out the audio first, which shows as a short “Preparing audio” step. A video with no audio track is reported as such.

Keys

Search: ⌘K
Panels: ⌘1 · ⌘2
Full width: F
All keys: ⌘/