Decibel meter (sound level meter)

The meter labels each reading with a plain-English description:

Approx. level	Example	Description
under 30 dB	Whisper, bedroom at night	Very quiet
30–45 dB	Library, quiet office	Quiet
45–60 dB	Normal conversation	Moderate
60–75 dB	Vacuum cleaner, busy street	Loud
75–85 dB	Heavy traffic, loud restaurant	Very loud
85+ dB	Concert, power tools, chainsaw	Harmful with long exposure

Decibels are logarithmic: an increase of 10 dB is roughly perceived as twice as loud, and every 3 dB doubles the sound energy.

Human hearing is less sensitive to deep bass and very high pitches than to the mid range. Frequency weighting adjusts the reading to match:

• A-weighting (dBA) follows how we hear moderate sounds and turns down low rumble. It is the standard for everyday noise, workplace exposure and hearing safety, so start here.
• C-weighting (dBC) is much flatter and keeps most of the bass. Use it for loud music, subwoofers and machinery hum, where low frequencies matter.
• Z-weighting (dBZ) applies no weighting at all.

If dBC reads much higher than dBA in the same spot, the noise is bass-heavy, like a neighbor's subwoofer or traffic rumble.

Your phone or laptop microphone was designed for voices, not measurement. It is not calibrated, and its sensitivity varies across frequencies, which also affects how well the weightings work. This tool turns off echo cancellation, noise suppression and automatic gain where the browser allows, and converts the signal to an estimated level using a default offset.

Treat readings as estimates that can be several decibels off. If you have a calibrated sound level meter, place both side by side in a steady noise, such as a fan, and move the Calibration offset slider until the values match. The offset applies to this session and device only. For workplace safety, legal disputes or noise ordinances, use a certified sound level meter.

The live number is smoothed over about a second, similar to the slow setting on a sound level meter, so it doesn't jump with every click. Peak hold keeps the highest reading on screen so a door slam or a dog bark isn't missed. Alongside it you get the lowest and highest levels since you started and an energy average (Leq), which weights loud moments properly instead of simply averaging decibel numbers.

The graph shows the last minute so you can spot recurring noises, such as music next door or a passing train. To keep a record, download the measurement log as a CSV file and open it in any spreadsheet app.

Turn on classroom noise monitor mode and set an alert threshold, for example 60 dB. When the level goes above it, the background turns red and a quiet-please message appears. Put the tablet or laptop where the class can see it. It works just as well in a shared office, a library or at home with kids.

No sound is recorded or uploaded; the signal is analyzed in your browser and discarded instantly.

If the reading stays at the bottom, the browser isn't getting sound. Allow the microphone from the site controls icon next to the address bar, check Windows 11 Settings › Privacy & security › Microphone or Mac System Settings › Privacy & Security › Microphone, and close apps that may be using the mic. The step-by-step microphone troubleshooter covers iPhone and Android too.

Noise at or above 85 dBA for long periods can permanently damage hearing, according to the U.S. National Institute on Deafness and Other Communication Disorders. Use hearing protection at concerts and with power tools. Curious about your own hearing? Try the hearing test.