Online decibel meter

How to measure decibels with this sound meter

1. Press Start and allow microphone access when the browser asks. The meter works on iPhone, Android, Mac and Windows in any current browser.
2. Hold the device at the spot you want to measure, microphone pointing at the source, without covering it with your hand or a case.
3. Read the big number: the current level in dB(A), refreshed several times a second with the standard "Fast" 125 ms time weighting.
4. Check Min, Avg and Peak for the session. "Avg" is the Leq, the energy-averaged level that noise regulations use, not a plain arithmetic mean.
5. Watch the chart for the last 60 seconds to see spikes: a door slam, a passing truck, a barking dog.

Nothing is recorded, stored or uploaded. The audio never leaves your device: the level is computed in the browser and discarded immediately.

How accurate is an online decibel meter?

Phone and laptop microphones are not calibrated instruments, so treat the reading as an estimate, typically within ±3 to 5 dB of a proper sound level meter in the 40–95 dB range. Three things limit accuracy:

• Microphone sensitivity differs between devices. If you can compare against a real meter, use the Calibration slider to add or subtract a fixed offset. The setting is remembered on this device.
• Automatic gain and noise suppression in the operating system can flatten loud sounds. The meter asks the browser to disable them, but not every platform honours the request.
• Very quiet and very loud extremes: most built-in microphones cannot resolve below about 30 dB, and they clip somewhere above 100–110 dB.

For a noise complaint, an occupational assessment or anything legal, use a certified Class 1 or Class 2 sound level meter. For everything else, from checking a nursery to comparing two fans, this tool is more than good enough.

What do the numbers mean?

The full decibel chart from 0 to 160 dB lists more examples, and every level from 30 to 140 dB has its own page under How loud is….

dB(A) or dB(Z)?

By default the meter applies A-weighting, the curve used by every noise regulation and most sound level meters. It discounts very low and very high frequencies the way human hearing does, so a rumbling bass and a hissing tweeter with the same energy do not read the same. Switch to dB(Z) for a flat, unweighted reading when you want to see the raw level, for example when checking a subwoofer. The difference between dBA, dBC and dBZ is explained in the guide.

Common uses

Frequently asked questions