Noise Meter (Approximate Sound Level in dB)
See how loud your surroundings are as an approximate dB reading from your microphone. Handy for checking how quiet a room is or comparing places. The reading is an estimate, not a calibrated instrument; you can tune it with the calibration offset below. Audio is neither saved nor uploaded. To check the microphone itself, use the Microphone Test.
🔒 Runs in your browser · Your data is never sent to a server
Press "Start measuring" and allow microphone access in the browser prompt.
Now-dB (approx.)
- Max
- -dB (approx.)
- Average
- -dB (approx.)
Last 30 seconds
The vertical axis spans 0 to 130 dB (approx.).
Calibration offset
This value is added to the microphone input level (dBFS) to get the displayed number. Sensitivity differs between devices, so compare against a reliable sound level meter and adjust.
Enter what another sound level meter shows for the same sound, then press the button while measuring to set the offset automatically.
Noise level guide
| Approx. dB | Feels like | Examples |
|---|---|---|
| Under 30 | Nearly silent | Rustling leaves, a quiet room late at night |
| 30-40 | Very quiet | A library, a quiet suburb at night |
| 40-50 | Quiet | A quiet office, an air conditioner indoors |
| 50-60 | Moderate | A quiet conversation, a distant vacuum cleaner |
| 60-70 | Somewhat noisy | Normal conversation, a busy office |
| 70-85 | Noisy | Inside a moving train, a vacuum cleaner, heavy traffic |
| 85+ | Very loud | Under an elevated railway, a construction site, a live concert (protect your hearing) |
How to use
- Press "Start measuring" and choose "Allow" in the browser prompt.
- Place your phone or PC where you want to measure and watch the current, max and average values and the graph.
- If needed, enter a reference meter reading and press "Match current sound" to set the calibration offset.
- Press "Reset max and average" to measure again, and "Stop measuring" when you are done.
Notes
- The numbers are approximate. Microphone sensitivity, the device and OS audio processing change the result a lot, so this is not suitable for legal noise measurement or proving equipment performance.
- The default offset (90 dB) is a placeholder chosen so that normal speech reads about 60 dB. Adjust it against a reference meter if you need better accuracy.
- Echo cancellation, noise suppression and auto gain control are all turned off for measuring, though some devices still apply processing of their own.
- Audio is used only to calculate the level. Nothing is recorded, saved or uploaded, and the microphone is released when you stop or close the page.
- Very loud or very quiet sounds are beyond what a typical microphone can capture accurately. Roughly 30 to 90 dB is the most reliable range.
Glossary
dB and dBFS
Decibels express loudness on a logarithmic scale. dBFS is relative to the maximum value of digital audio (0). Without knowing the microphone sensitivity it cannot be converted to real sound pressure (dB SPL), so a calibration offset is added to give an estimate.
Average (Leq)
The equivalent continuous sound level: the steady level that carries the same energy as the varying noise. Loud moments weigh more than in a plain average. The "Average" here is calculated this way.
Calibration offset
The value added to the microphone level (dBFS) so that it approximates the real sound level in dB. You set it by measuring the same sound with a reference meter.
FAQ
How accurate is the dB reading?
It is an estimate. Microphone sensitivity and your device’s audio processing change the number, so it cannot replace a calibrated sound level meter. Measure the same sound with a reference meter and tune the calibration offset to get closer.
How do I set the calibration offset?
Measure the same sound in the same place with a reference meter (or a trustworthy meter app), type its value into "Reference meter reading" and press "Match current sound". The offset is device-specific, and it returns to the default when you reload the page.
Is the audio recorded or sent anywhere while measuring?
No. The microphone signal is used only to calculate the level. Nothing is recorded, saved or uploaded, and the microphone is released when you stop or close the page.
The reading never reaches zero, even in a silent room.
The microphone’s own electrical noise and your device’s audio processing set a floor. Treat values below about 30 dB as unreliable and use them only to compare how quiet places are.
Is "Average" a plain average?
No. It uses the equivalent continuous sound level (Leq) approach used in noise assessment: the sound energy is averaged and then converted back to dB. Loud moments push it above a simple arithmetic mean.
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