Online Decibel Meter

Measure sound in your browser

This online decibel meter reads your microphone through the Web Audio API and shows live input strength immediately — no download, no account. Press Start Measuring, grant permission once, and watch current, average and peak values on the live graph. For an estimated environmental sound level, calibrate your microphone against a known reference first.

How the online decibel meter works

Each audio block is reduced to an RMS value, converted to a level in dB, corrected for the selected frequency weighting, smoothed with Fast (125 ms) or Slow (1 s) time response, and aggregated into an energy-average Leq. Uncalibrated output is microphone input strength; a saved offset turns it into an estimated environmental reading. Read the full methodology.

Understanding your measurement

Raw digital readings (dBFS) are negative because full scale is zero — silence sits near −100 and loud input approaches 0. This meter maps that range to a 0–100% input-strength display so it stays readable. Environmental decibels work the other way: a quiet bedroom is around 30 dBA and normal conversation near 60 dBA. See understand decibel levels for approximate examples.

Calibrating for estimated environmental decibels

Every microphone has different gain, so calibration is required before any dBA number can be trusted. Place the device where you will measure, play or compare a stable reference of known level, enter the difference as an offset, and keep the same microphone, position and settings. Profiles are device-specific and stop applying when the setup changes. Follow the calibration guide.

What A, C and Z weighting mean

Sound-level weighting shapes which frequencies count most. A-weighting (dBA) approximates human hearing and is the default for everyday checks; C-weighting (dBC) stays flatter near loud peaks; Z-weighting (dBZ) counts all frequencies equally. Fast response follows peaks, Slow smooths them. Compare them in dB vs dBA.

Browser measurement accuracy

Phone and laptop microphones are not calibrated instruments: gain, placement and frequency response differ per device. This tool reports an honest browser estimate, never a certified reading. Compare against a known reference to add an offset, and use a calibrated meter for safety, workplace or legal decisions.

Read the full browser measurement accuracy guide →

Microphone privacy

The browser processes microphone samples locally; this site uploads no recordings and sets no tracking cookies for measurement. Saved session history stays in this browser. Details inmicrophone privacy.

Measure in three steps

1. 01

   Allow the microphone

   Press Start and grant permission when the browser asks. Audio stays on your device.

2. 02

   Watch the live panel

   Read current, average and peak input strength, or calibrated sound-level statistics, with the matching live graph.

3. 03

   Tune and export

   Pick weighting and response, optionally calibrate, then export CSV or JSON.

New here? Read how to use the meter or fix microphone problems.

Microphone permission troubleshooting

If permission was denied, open the lock/tune icon in the address bar and allow the microphone, then press Start again. If no device appears, connect one and reload. If another app holds the mic (calls, recorders), close it first.

Microphone troubleshooting →

Sessions & export

Each run keeps duration and mode-aware session statistics. Percentage feedback stays visual-only; environmental estimates are exported only when compatible calibration is active.

Common questions