Beat Detection Tool
Detect the BPM (beats per minute) of any music or rhythmic sound in real time using your microphone or by uploading an audio file. See beat pulses, tap along to verify, detect time signatures, and explore genre BPM ranges — all processed locally in your browser.
Beat Detection Tool
| Genre | BPM Range | Typical |
|---|---|---|
| Hip-Hop / Trap | 60–90 | ~80 |
| R&B / Soul | 70–100 | ~85 |
| Reggae / Dub | 70–100 | ~80 |
| Pop | 100–130 | ~120 |
| House | 120–130 | ~125 |
| Techno | 125–150 | ~135 |
| Dubstep | 130–145 | ~140 |
| Drum & Bass | 160–180 | ~174 |
| Rock / Alternative | 100–140 | ~120 |
| Metal | 100–180 | ~140 |
| Jazz | 80–200 | ~130 |
| Classical | 40–200 | varies |
| Time | BPM | Interval (ms) | Confidence |
|---|
How to Use the Beat Detection Tool
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Choose Your Input Mode
Select Microphone to detect beats from live audio, Audio File to analyze an uploaded song, or Tap Tempo to manually tap along with a beat. Each mode has its own optimized workflow.
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Start Listening or Upload a File
For microphone mode, click "Start Listening" and play music near your device. For file mode, drag and drop an MP3, WAV, or FLAC file. The tool will analyze the entire file and detect the BPM.
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Read the BPM Display
The large BPM number shows the detected tempo. The beat pulse ring flashes on each detected beat. The confidence indicator shows how reliable the reading is — higher confidence means a clearer, more consistent beat pattern.
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Verify with Tap Tempo
Switch to Tap Tempo mode and tap along with the music to cross-check the detected BPM. You can also press T on your keyboard. The tool averages your tap intervals for an accurate manual reading.
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Explore Results & Export
Check the genre match to see which music genre fits your BPM. Review the BPM history chart for tempo changes over time. Use 📋 Copy BPM or 💾 Export CSV to save your results.
Understanding Your Results
BPM Display
The main number shows the detected beats per minute — the tempo of the music or rhythmic sound. It updates in real time as the algorithm locks onto the beat. The beat pulse ring flashes green on each detected downbeat, giving you visual confirmation.
Confidence Indicator
The confidence rating tells you how reliable the BPM reading is. High confidence means a clear, repetitive beat pattern was detected. Lower confidence can occur with complex rhythms, ambient music, speech, or very quiet signals.
Time Signature Detection
The tool analyzes the accent pattern of detected beats to estimate the time signature. Common results include 4/4 (most pop and electronic music), 3/4 (waltz), and 6/8 (compound time). This feature works best with clear downbeats and accents.
Energy Waveform
The waveform shows the energy envelope of the audio signal with red markers on detected beats. This helps you visually verify that beats are being detected at the right positions — beat markers should align with the loudest transients in the waveform.
BPM History Chart
This rolling chart tracks BPM over the last 30 seconds. A flat line indicates a steady tempo (typical of electronic music). A varying line indicates tempo changes (common in live performance, jazz, and classical music).
Genre Match
Based on the detected BPM, the tool shows which music genres typically use that tempo range. This is useful for DJs selecting compatible tracks, producers targeting a genre, or curious listeners learning about music styles.
How Beat Detection Works
Musical tempo is the rate of recurring beats in a piece of music, measured in beats per minute (BPM). This tool uses a multi-stage algorithm to detect beats from raw audio in real time.
Onset Detection via Spectral Flux
The first stage computes the spectral flux — the amount of change in the frequency spectrum between successive audio frames. A sudden increase in spectral energy (particularly in the bass and midrange bands) signals a beat onset. The algorithm applies a dynamic threshold that adapts to the overall energy level, preventing false positives in quiet passages and missed beats in loud ones.
Autocorrelation for Tempo Estimation
The detected onsets form a binary signal (beat / no-beat over time). The tool computes the autocorrelation of this onset signal to find the most likely periodicity — the interval at which beats repeat most consistently. This gives a robust BPM estimate that handles syncopation, ghost notes, and off-beat accents better than simple peak-counting.
Tempo Octave Disambiguation
A common challenge in beat detection is octave errors — confusing 60 BPM with 120 BPM, or 80 with 160. The tool uses heuristic weights that favor the 80–160 BPM range (where most music falls) and checks for sub-harmonics to pick the musically correct tempo.
Tap Tempo Algorithm
In tap mode, the tool records the time between each tap, discards outliers (taps that are >2× or <0.5× the median interval), and computes the trimmed mean of the remaining intervals. This gives a stable BPM reading after just 4–6 taps.
Frequently Asked Questions
What BPM range can this tool detect?
The tool detects tempos from 40 BPM to 220 BPM, covering everything from slow ballads and ambient music to fast drum and bass and speed metal. The algorithm is optimized for the 80–180 BPM range where most popular music falls.
How accurate is the BPM detection?
For music with a clear, consistent beat (pop, EDM, hip-hop, rock), accuracy is typically within ±1 BPM after 10–15 seconds of listening. Complex rhythms, live performances with tempo rubato, or very quiet audio may produce slightly less precise results. Use tap tempo to verify.
Can I detect the BPM of a song playing on my computer?
Yes! Either use the Audio File mode to upload the song directly, or select "Stereo Mix" as your microphone input to capture system audio. Stereo Mix availability depends on your sound driver — check your system's sound settings.
Why does it sometimes show double or half the BPM?
This is called an octave error and happens when the algorithm interprets every other beat as the primary beat (halving the BPM) or counts sub-beats (doubling it). The tool uses heuristics to minimize this, but if the result seems off, try tap tempo to confirm the correct tempo, or adjust the sensitivity slider.
What audio file formats are supported?
The tool supports any format your browser can decode: MP3, WAV, OGG, FLAC, AAC, M4A, and WebM. Files up to 50 MB are accepted. The entire file is decoded and analyzed client-side — nothing is uploaded to any server.
How does tap tempo work?
Click or tap the TAP button (or press T) in rhythm with the music. After 4+ taps, the tool calculates the average interval between taps and converts it to BPM. It automatically discards outlier taps that are too fast or too slow. The more taps you give, the more accurate the reading.
Can this detect tempo changes within a song?
Yes. The BPM History chart shows tempo changes over time. If a song speeds up or slows down, you'll see the line rise or fall. This is common in live recordings, classical music, and progressive compositions. The tool continuously re-estimates BPM in real time.
Is my audio data safe?
Completely safe. All beat detection and audio processing happens 100% in your browser using the Web Audio API. No audio is recorded, stored, or sent to any server. Uploaded files are decoded locally and never leave your device.
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