Decibel Sound-Level Meter
Measure how loud your room really is in dB using your microphone — live gauge, 60-second history graph, peak/average stats and a hearing-safety warning.
Measure the sound around you
Tap Start and allow microphone access. Audio is analysed in real time on your device and never leaves it.
Browsers can't read true calibrated SPL, so this reading is approximate. Slide to match a known reference (e.g. another sound-level meter or app).
🔒 100% private — your microphone audio is processed entirely in your browser and is never recorded, uploaded or sent anywhere. Readings are an approximation for awareness, not a certified measurement.
Why you’ll love Decibel Sound-Level Meter
Instant & free
No signup, no paywall, no limits — Decibel Sound-Level Meter works the moment the page loads.
Completely private
Everything runs in your browser. Nothing you enter is ever uploaded or stored on a server.
Works on any device
Fully responsive and touch-friendly — use it on your phone, tablet or desktop.
Uses your real device
Taps into your actual camera, mic or motion sensors — right in the browser.
How to use it
Open it
No download and no login — the tool is ready right at the top of this page.
Use it
Enter your details or start interacting. Everything updates live as you go.
Get your result
Copy, download or share your result in a single tap. That’s it.
About Decibel Sound-Level Meter
This meter turns your device's microphone into a live sound-level readout. It requests the mic with auto-gain, echo cancellation and noise suppression disabled so the signal is honest, computes the RMS level of the raw waveform many times per second, and converts it to an approximate decibel SPL figure shown on a 270° gauge with a scrolling 60-second history graph, plus min, average, max and peak-hold statistics for the session.
Because browsers cannot read a microphone's true calibrated sensitivity, the reading is an approximation — so the tool includes a calibration panel. If you know the real level (from a dedicated SPL meter or a known reference), enter it and tap "Calibrate to this"; the offset is saved on your device for next time. You can also switch between Z-weighting (flat, all frequencies counted equally) and A-weighting, the standard curve that de-emphasises very low and very high frequencies to match how the human ear perceives loudness.
The meter watches for hearing risk as it measures. Sustained levels of 85 dB or more trigger a safety banner with a NIOSH-style safe-exposure estimate: 85 dB is considered safe for about 8 hours, and every 3 dB louder halves that time — so 100 dB gives you roughly 15 minutes. A reference scale from whisper (30 dB) to pain threshold (120 dB) highlights where your room currently sits.
Everything happens locally: the audio is analysed in real time in your browser, never recorded, stored or uploaded, and the microphone is automatically released the moment you stop the meter or switch tabs.
Popular uses
Frequently asked questions
Uncalibrated, expect readings within roughly ±5–10 dB of a professional SPL meter, because every microphone has different sensitivity and browsers do not expose calibration data. This tool improves on typical apps by disabling automatic gain control (which would flatten loud and quiet sounds) and by letting you calibrate against a known reference. After calibrating to a real meter in the same room, relative readings — quieter vs louder, before vs after — become quite dependable.
Z-weighting is "zero" weighting: every frequency counts equally, which suits measuring raw acoustic energy. A-weighting applies the standard IEC curve that mimics human hearing, reducing the contribution of deep bass and very high frequencies. Occupational noise limits, hearing-safety guidance and most published noise levels are quoted in dB(A), so switch to A-weighting when comparing your room against those numbers.
The NIOSH recommendation is 85 dB(A) averaged over an 8-hour day. Above that, each 3 dB increase halves the safe exposure time: 88 dB is safe for about 4 hours, 94 dB for 1 hour, 100 dB for 15 minutes and 110 dB — typical of a loud concert — for under 2 minutes. This meter applies exactly that formula and shows the estimated safe time whenever it detects sustained levels of 85 dB or more.
Play or find a steady sound, check its true level on a reference (a dedicated SPL meter, or a calibrated meter at work), then type that value into the "I know it's actually…" field while this meter is running and tap "Calibrate to this". The tool computes the offset and remembers it on your device. Without a reference, the default offset gives sensible ballpark readings on most phones and laptops.
The big number is a smoothed live level, which is easier to read than the raw signal. Min, avg and max summarise the whole session since you pressed Start (or last reset). Peak is a fast detector that grabs brief spikes — a door slam or a clap — before smoothing hides them, then decays back down; a yellow marker on the gauge holds the recent peak position for a moment.
Decibel Sound-Level Meter is 100% free — no signup, no watermarks and no usage limits. It’s one of 200+ free tools we build and give away.
No. All sensor data is processed live on your device and never leaves it or gets stored.
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