Decibel Meter
A sound level meter in your browser. Readings are estimates; calibrate for better ones.
--dB(A)
Press Start measuring and allow microphone access.
- Min
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- Average
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- Max
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Match a calibrated meter, then leave it. Saved in this browser.
How to use the decibel meter
- Press Start measuring and allow microphone access.
- Hold the device still, with the microphone pointing at the sound and nothing covering it. On most phones the mic is on the bottom edge.
- Watch the reading for a while. Average shows the energy average (Leq) since you pressed Start, Max the loudest moment.
How accurate is a phone or laptop decibel meter?
Honestly: roughly. A real sound level meter has a measurement microphone calibrated against a known reference. Phone and laptop microphones are built for voice. They differ from model to model, some cut low bass, and many compress or limit loud sound. This page turns off the browser's echo cancellation, noise suppression and automatic gain where the browser allows it, applies an approximate A-weighting and uses a fast time constant of 125 ms, like the Fast setting on a hardware meter.
Without calibration, expect readings within about 5 to 10 dB of the truth in normal rooms, and less reliable values above about 100 dB, where small microphones start to distort. The reading is good for comparing: is the street louder than the office, did the new fan make the room quieter, is the music louder than last week.
To calibrate, put a calibrated meter next to your device, play a steady sound such as pink noise or a fan, and move the offset slider until both read the same. The offset is saved in your browser and applied every time.
What the numbers mean
Decibels are logarithmic: 10 dB more sounds about twice as loud and carries ten times the energy. Hearing damage depends on level and time. At 85 dB(A) the usual safe limit is 8 hours a day; every 3 dB more halves that time. Use the reference ladder next to the meter to put a reading into context.
Questions and answers
How accurate is this decibel meter?
It is an estimate. Phone and laptop microphones are not calibrated, and many filter or limit loud sound. Expect readings to be off by 5 to 10 dB until you calibrate against a real sound level meter. Use it to compare levels, not for legal or workplace measurements.
How do I calibrate it?
Measure a steady sound with a calibrated sound level meter and with this page at the same spot. Move the calibration slider until both show the same value. The offset is saved in your browser for next time.
What does dB(A) mean?
dB(A) is a sound level with A-weighting, which turns down low and very high frequencies the way human hearing does at moderate levels. Most noise limits and hearing-safety rules are written in dB(A).
How loud is too loud?
Sound above 85 dB(A) can damage hearing over hours, and every 3 dB more halves the safe time: about 8 hours at 85 dB, 2 hours at 91 dB and less than 15 minutes at 100 dB.
What is the difference between average and maximum?
Maximum is the loudest moment since you pressed Start. Average is an energy average (Leq), which is how noise exposure is normally measured, so short loud bursts raise it more than a plain average would.