Decibel meter

Measure how loud it is right now with your phone or laptop microphone. Press Start, allow the microphone, and the pen draws the last 30 seconds. Nothing is recorded.

–dB(A)

Press Start and allow microphone access. Audio stays on your device.

Average (Leq)
–
Max
–
Min
–
Time
0:00
Calibrate (offset 100 dB)
100 dB

Browsers only report how loud the signal is inside the device, not the sound pressure in the room. The default offset of 100 dB is a starting guess, not a measurement. To calibrate, play a steady sound next to a real sound level meter and move the slider until both show the same number. The setting is saved in this browser.

What the numbers mean

Typical levels from the US National Institute on Deafness and Other Communication Disorders (NIDCD). Long or repeated exposure at or above 85 dBA can cause hearing loss.

How to get a useful reading

  1. Hold the phone or laptop still, microphone uncovered, at about ear height.
  2. Leave it running for at least a minute. The average (Leq) settles; the live number never does.
  3. Use A-weighting (the default) to compare with hearing-safety limits. Switch to Z to see bass and rumble.
  4. Write down the average and the max, with the time. That is what a landlord, council or doctor will ask for.

How accurate is a phone or laptop?

Closer than you might expect, if the device is calibrated. NIOSH researchers tested smartphone sound apps against a professional meter: of 192 apps, 10 met their selection criteria, and 4 of those stayed within ±2 dB of the reference. The iOS apps did better than the Android ones. With an external calibrated microphone, the agreement got even closer, within about ±1 dB in their tests.

A browser meter has one more catch: browsers report the level relative to the device's own maximum, not the sound pressure in the room. That is why this meter has a calibration offset. Without calibration, treat the number as a good guide for "louder or quieter than before", not as proof.

Need a number that holds up? Read how to choose a real sound level meter.

Questions

Is an online decibel meter accurate?
It is good for comparing sounds and spotting changes, not for legal or workplace proof. Browsers report the level inside the device, so the reading depends on your microphone and the calibration offset. Set the offset against a real sound level meter for numbers you can trust within a few decibels.
Does this decibel meter record or upload audio?
No. The audio is analysed in your browser and thrown away straight after. Nothing is stored or sent to a server.
What is the difference between dB(A) and dB(Z)?
dB(A) filters the sound the way human hearing does, so very low and very high pitches count for less. Hearing-safety limits such as the NIOSH 85 dBA limit use A-weighting. dB(Z) is flat, with no filter, and shows more of the low rumble from traffic or bass.
What does Leq mean?
Leq is the energy average of the level over the whole measurement. One loud bang raises it more than a plain average would, which is why noise limits are usually written as an average level over time.
Why does it ask for microphone permission?
The meter needs the microphone signal to measure sound. If you block it, nothing is measured. You can turn the permission off again in your browser settings at any time.

Noise guides

Sources