Online Decibel Meter
Press Start and this page measures the sound level around you, in decibels, using your device microphone. It runs entirely in your browser — no audio is recorded or uploaded. Readings are uncalibrated estimates (about ±10 dB); for calibrated accuracy you need a dedicated meter or a calibrated app.
Nothing is recorded or uploaded — the analysis runs entirely in your browser.
Defaults are tuned per device; nudge until it matches a reference meter you trust. Saved on this device.
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What this tool does
The meter reads your microphone with the Web Audio API about ten times a second, converts the signal energy to decibels, and applies a fixed offset to approximate sound pressure level (dB SPL). You get a live readout, the session minimum, average, and maximum, and an optional A-weighting filter that approximates how human hearing emphasises mid-range frequencies — the same weighting, written dB(A), that noise regulations use.
How accurate is it?
Honest answer: it is an estimate, not a measurement instrument. Phone and laptop microphones are built for voice, not metrology, and none of them are calibrated. Expect readings within roughly ±10 dB of a true SPL meter, with the largest errors at very quiet and very loud extremes. That is plenty to answer “is this room around 60 dB or 90 dB?” — it is not evidence for a noise complaint or an OSHA/NIOSH compliance check. The default offset is tuned per device class — iPhone microphones report quieter signals than laptop microphones for the same sound — and the calibration control under the meter lets you nudge readings to match a reference meter you trust. The FAQ explains how phone meters compare to dedicated SPL meters.
Your privacy
Everything happens locally in your browser tab. The audio stream is analysed in memory and discarded — there is no recording, no upload, no server. Close the tab and it is gone.
Reference points
30 dB is a soft whisper, 60 dB a normal conversation, 85 dB the level at which NIOSH says sustained exposure starts damaging hearing, and 110 dB a loud concert. The full decibel levels chart lists 30+ common sounds with sourced ranges, and the city sound map ranks the estimated noise levels of 50 major cities.
On your phone? Decibel Shield for iOS adds adjustable calibration, measurement history, Apple Health sync, and exposure alerts. Scan to open the App Store.
Common questions
How accurate is an online decibel meter?
Browser and phone microphones are not calibrated, so treat readings as estimates within roughly ±10 dB. They are good for comparing situations — is the bar louder than the street? — not for legal or occupational measurements, which require a calibrated SPL meter.
What decibel level is dangerous?
NIOSH sets the workplace recommended exposure limit at 85 dB(A) averaged over 8 hours; every 3 dB increase halves the safe time. Above roughly 100 dB, damage is possible in minutes. 120 dB and up risks immediate injury.
Why do decibel apps show different readings?
Different microphones, different weighting filters, different averaging windows, and different calibration offsets. Two uncalibrated devices can easily disagree by 5–10 dB on the same sound. Hardware calibration, like dedicated meters use, is what closes the gap.