Online decibel meter

How to measure sound level in your browser

The meter reads your microphone, calculates the RMS energy of the signal many times a second, and converts it to a decibel figure. Press start, allow the permission prompt, and leave it running for ten to fifteen seconds before reading anything — short bursts are noise, the settled average is the measurement.

1. Place the laptop or phone where you actually care about the noise, not next to the source.
2. Keep your hands off the device; handling noise dominates the reading.
3. Stay silent for the first ten seconds to establish the room's noise floor.
4. Read the running average rather than the peak.

Reading the number

Decibels are logarithmic, which is the part that trips everyone up. A 10 dB rise is about twice as loud subjectively but ten times the sound energy. Two identical sources together add only about 3 dB, not double the number. The decibel levels guide works through the arithmetic and the safe-exposure tables in detail.

What a browser meter is genuinely good for

• Finding the quietest room for a call, a recording, or a study session. Walk between rooms with the meter running and compare.
• Identifying a specific noise source. Switch appliances off one at a time and watch how far the floor drops. Fridges, air purifiers, and desktop fans are usually the biggest offenders.
• Establishing your recording noise floor. Under 40 dB and your microphone can be a metre away; above 50 dB and it needs to be close.
• Checking whether a fix worked. Rugs, curtains, and door seals produce measurable changes.
• Comparing headphone leakage or keyboard noise before a call.

What it is not good for: proving a neighbour is too loud, documenting workplace exposure, or anything with legal weight. Those require a calibrated Type 1 or Type 2 sound level meter.

Why your phone's app shows a different number

Several things pull browser readings away from a dedicated meter:

• Unknown microphone sensitivity. A studio microphone and a laptop array can differ by more than 20 dB for the same sound.
• Automatic gain control. This tool asks the browser to disable AGC, but some operating systems and drivers apply it anyway. If your reading drifts back toward a constant value after a loud sound, AGC is active.
• No frequency weighting. Real meters apply A-weighting to match human sensitivity across frequency. This meter is unweighted, so it over-reports low-frequency noise such as traffic rumble or HVAC.
• Microphone placement. A laptop microphone points at your face, past the keyboard, often through a mesh. That alone shifts readings by several decibels.
• Ceiling and floor. The signal is clamped between 20 and 100 dB, so extremes are compressed.

If two meters disagree, trust neither absolutely — but trust the difference each one reports between two conditions, because that part is reliable.

Making a room measurably quieter

Run the meter, make one change, run it again. Changes worth trying, roughly in order of effect per unit of effort:

• Turn things off. Fans, air purifiers, secondary computers. The largest single win in most rooms.
• Close the door and windows, then seal the gap under the door. Low-frequency traffic noise arrives mostly through gaps.
• Add soft mass. Rugs, curtains, and a bookshelf on the reflective wall reduce reverberation, which makes speech clearer even when the measured level barely changes.
• Move away from the noise. Doubling your distance from a point source drops the level by about 6 dB — usually cheaper than any acoustic treatment.
• Move the microphone, not the room. Halving the distance from your mouth to the microphone gains about 6 dB of signal, which improves the signal-to-noise ratio just as effectively as silencing the room.

Once the room is as quiet as it will get, check how you sound in it with the record and playback tool.

Frequently asked questions