Sound Level Meter
The meter turns microphone samples into decibels: estimated dB equals dBFS plus a calibration offset you can adjust. It shows the live level with the max, average and min since you started.
How to use
- Press Start measuring and allow microphone access. The tool asks the browser to switch off noise suppression, echo cancellation and automatic gain.
- Read the estimated dB, with the max, average and min since you started. Press Reset to begin a new measurement, or Set baseline to see how much louder or quieter things get.
- For numbers closer to the truth, calibrate: play a steady sound beside a real sound level meter, type its reading in Reference reading and press Match reference.
How it works
The browser hands the tool raw samples from the microphone. Many times a second it takes the root mean square (RMS) of the latest samples and converts it to decibels relative to full scale: dBFS = 20 x log10(RMS). 0 dBFS is the loudest value a digital signal can hold, so readings are negative.
Estimated dB = dBFS + calibration offset. The microphone in a phone or laptop has an unknown sensitivity, so no single offset is right for every device. With the offset at 0 the number is only a relative level, not a sound pressure level (dB SPL). Calibrating against a reference meter at one level makes the readings roughly usable near that level.
The display uses a Fast time weighting of 125 ms. Max and Min follow that smoothed value, and Average is the energy average (Leq): 10 x log10 of the mean of 10^(dB/10). The signal is unweighted, so the values are not dBA.
Typical sound levels
Example levels from the U.S. National Institute on Deafness and Other Communication Disorders (NIDCD), in A-weighted decibels (dBA). Sources: nidcd.nih.gov/health/noise-induced-hearing-loss and cdc.gov/niosh/noise/about/index.html
- Sounds at or below 70 dBA are unlikely to cause hearing loss, even after long exposure (NIDCD).
- Long or repeated exposure to sounds at or above 85 dBA can cause hearing loss (NIDCD). NIOSH recommends 85 dBA averaged over an eight-hour workday as its occupational exposure limit.
| Sound | Level (dBA) |
|---|---|
| Normal conversation | 60 to 70 |
| Movie theater | 74 to 104 |
| Motorcycles and dirt bikes | 80 to 110 |
| Headphones at maximum volume, sports events, concerts | 94 to 110 |
| Sirens | 110 to 129 |
| Fireworks show | 140 to 160 |
FAQ
Is this reading accurate?
Not as it comes. Built-in microphones differ in sensitivity, and phones and browsers often add automatic gain or limiting, so uncalibrated values are only relative. After calibrating at one level it is a reasonable estimate close to that level. It is not a certified instrument and should not be used for medical, legal or workplace compliance decisions.
Why does an iPhone read differently?
Safari on iPhone and iPad applies its own input processing and may ignore the request to turn it off, and the microphone response differs by model. Use it to compare relative changes rather than absolute numbers.
Is anything recorded or uploaded?
No. The level is computed in your browser. No audio is stored or sent anywhere.
Why is my reading far from the table below?
The table lists A-weighted sound levels measured with calibrated equipment. This tool shows an unweighted estimate that depends on your offset, so the two are not comparable until you calibrate.