Online Tool Store
Sound Level Meter
Estimate the ambient sound level around you in real time using your microphone, with a live decibel reading, peak, average, and a loudness rating. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
-- dB
Microphone is idle. Start to measure ambient sound.
Peak
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Average
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Rating
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How the sound level meter works
- Press Start and allow microphone access when your browser asks.
- The tool reads your microphone's live audio buffer many times per second.
- Each buffer is converted into an estimated decibel level, shown live along with a running peak and average.
The method
The Web Audio API's AnalyserNode exposes the raw waveform samples for each audio buffer. The tool computes the root-mean-square (RMS) amplitude of that buffer, then converts it to a relative decibel scale using a logarithmic formula.
dB ≈ 20 × log10(RMS) + 100
The +100 offset maps the microphone's relative amplitude scale onto a range that resembles typical SPL readings for everyday sounds - it is a convenient reference point, not a calibrated absolute measurement.
FAQ
How accurate is this compared to a real decibel meter?
It is an estimate. Consumer microphones and browsers are not calibrated like a professional sound-level meter (an SPL meter), so treat the reading as a relative indicator, not a certified measurement.
Why does my browser ask for microphone permission?
The tool needs live access to your microphone input to measure sound levels. Audio is analyzed locally and is never recorded, saved, or uploaded.
What do Peak and Average show?
Peak is the loudest reading seen since you pressed Start. Average is the mean decibel level across the whole measuring session.
Can I use this to check if a room is safe for hearing?
Use it only as a rough guide. For occupational or medical decisions, use a calibrated sound-level meter or dosimeter.
How we compare
| Feature | Online Tool Store | Native phone SPL apps | Dedicated SPL meter |
|---|---|---|---|
| No app install | ✓ | ✗ | ✗ |
| Free | ✓ | Often paid | Hardware cost |
| Calibrated absolute accuracy | ✗ | ✗ | ✓ |
For a quick, free check of relative noise levels without installing anything, Sound Level Meter is the fastest option.