Decibel Meter (Sound Level Meter)
Measure sound level with your microphone or a recording: A, C or Z weighting, fast or slow, with Leq, maximum, minimum and L90 background level.
Estimate how loud it is around you with your phone or computer microphone, or measure the level of a recording. The meter applies the standard A, C or Z frequency weighting and fast or slow time weighting, then reports the average (Leq), the maximum and minimum, and the background level L90. Because consumer microphones are not calibrated, readings are estimates; a calibration offset lets you match a real meter.
How to use this tool
- Choose the microphone (or a recording) and how long to measure.
- Leave A-weighting and Fast for everyday noise; choose C for loud music or machinery.
- Press Calculate and allow the microphone. Hold the device still, pointing at the sound, away from your mouth.
- If you have a real sound level meter, adjust the calibration offset until both agree, then keep that offset for this device.
Formula
L = 10 × log10(mean of the weighted signal²) + offset · Leq over the whole measurement
A- and C-weighting use the IEC 61672 pole frequencies (20.6, 107.7, 737.9 and 12,194 Hz) turned into digital filters. They follow the standard curve within 0.1 dB up to 5 kHz and fall slightly below it higher up (about −1.2 dB at 10 kHz), so the microphone, not the filter, is the main source of error. Fast and slow are exponential averages with 125 ms and 1 s time constants; L90 is the level exceeded 90% of the time, the usual measure of background noise. The offset turns digital level (dBFS) into dB; its 95 dB default is an assumption, not a calibration.
Example
If the microphone delivers a steady RMS level of −35 dBFS (A-weighted) and the offset is the default 95 dB, the reading is −35 + 95 = 60 dB(A), about normal conversation at one metre. If a real meter beside the phone shows 66 dB(A), set the offset to 101 dB.
Frequently asked questions
How accurate is a phone decibel meter?
Without calibration the error depends on the microphone and on how far the 95 dB default is from its real sensitivity: 10 dB or more is common. Phones also limit very loud sounds and some browsers apply processing. Calibrating against a real meter at a steady level makes readings much more consistent, but a phone or laptop still does not become a class 1 or 2 meter.
What is the difference between dB(A) and dB(C)?
A-weighting reduces low and very high frequencies the way our ears do at moderate levels, so it is used for most noise limits. C-weighting is nearly flat and suits loud events where bass matters, such as concerts.
How loud is too loud?
Long exposure above about 85 dB(A) can damage hearing over time; many workplaces must act above 80–85 dB(A). Use a certified meter for any decision that matters.
Readings come from a phone or computer microphone that is not calibrated, so they are estimates only: with the default offset they can easily be 10 dB or more off. Do not use them for hearing protection, occupational (workplace) noise assessment, legal limits or noise complaints: use a calibrated sound level meter (IEC 61672 class 1 or 2) for that. How we check our calculators · Full disclaimer
Last updated:
Page address with these inputs: https://kakao.mobile/tools/decibel-meter/
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kakaoCalc. (2026, November 8). Decibel Meter (Sound Level Meter). https://kakao.mobile/tools/decibel-meter/
“Decibel Meter (Sound Level Meter).” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/decibel-meter/.