How to measure sound with this decibel meter
- Press Start measuring and choose Allow when the browser asks for the microphone. Nothing is recorded: the page only computes levels.
- Hold your phone or laptop still, microphone pointing at the sound, and keep your hands and clothes off it — rubbing the microphone reads as loud noise.
- The big number is the current level. Minimum, Average (Leq) and Maximum cover everything since you started or last pressed Reset; the graph shows the last 60 seconds.
- For a fair average of a varying noise (traffic, a neighbor’s music, a classroom), measure for at least a minute or two.
What the numbers mean
- dB(A) is the sound level A-weighted: the meter filters the sound the way the IEC 61672 standard prescribes, playing down low and very high frequencies that human ears hear less well. Most noise limits and hearing-safety rules are written in dB(A).
- Fast is the response speed of a sound level meter: the display follows the sound with a 125-millisecond time constant, so a door slam shows up but the number doesn’t jitter with every syllable.
- Average (Leq) is the equivalent continuous level: the steady level that would carry the same sound energy as everything measured. Decibels are logarithmic, so the meter averages energy, not the numbers — one minute at 90 dB(A) plus nine minutes at 60 dB(A) average to 80.0 dB(A), not 63; and two equal halves at 60 and 80 dB(A) give 77.0 dB(A), not 70. Loud moments dominate, which is exactly how they affect hearing.
- Unweighted level, A-weighted level and Highest peak are the raw readings in dBFS (decibels relative to the microphone’s full scale), before any conversion to sound pressure.
| Frequency | A-weighting |
|---|---|
| 31.5 Hz | -39.4 dB |
| 63 Hz | -26.2 dB |
| 125 Hz | -16.1 dB |
| 250 Hz | -8.7 dB |
| 500 Hz | -3.2 dB |
| 1,000 Hz | 0.0 dB |
| 2,000 Hz | 1.2 dB |
| 4,000 Hz | 1.0 dB |
| 8,000 Hz | -1.1 dB |
The table shows how much the A-filter lowers each frequency (IEC 61672-1). A 63 Hz hum counts about 26 dB less than a 1,000 Hz tone of the same physical strength. The meter’s digital filter matches this curve within about 0.2 dB from 20 Hz to 10 kHz.
How accurate is a phone or computer decibel meter?
Honestly: it is an estimate. A browser only gets numbers relative to the microphone’s maximum (dBFS), never sound pressure. Turning them into dB SPL needs to know how sensitive your microphone is and how much gain the system adds — and no website can read that. This meter starts from the typical specification of the digital MEMS microphones built into phones and laptops (a 94 dB tone reads about 26 dB below full scale) and adds your calibration offset.
- Voice processing is switched off. The meter asks the browser to disable automatic gain control, noise suppression and echo cancellation. Gain control would raise a quiet room and turn down a loud one; noise suppression removes steady noise such as a fan — both would make the readings meaningless. A few devices ignore the request; the meter warns you when it notices.
- Loud sounds clip. Phone microphones are built for speech and typically saturate somewhere around 110–120 dB. When the input reaches full scale the meter warns you: the real level is higher than displayed.
- Quiet rooms read too high. Below roughly 30–40 dB(A) the microphone’s own noise is louder than the room, so the minimum can’t go lower.
- Frequency response varies. Small microphones and phone cases change the sound, especially in the bass. Treat differences under 3–5 dB with caution.
This page is not a certified sound level meter and must not be used for legal, workplace or compliance measurements. Those need a calibrated Class 1 or Class 2 instrument (IEC 61672) operated by someone trained in the method.
Calibrating your device
If you can borrow a sound level meter, or someone has one, place both side by side in front of a steady sound such as a fan or pink noise from the white noise generator at a moderate volume. Read both after about 30 seconds. If the meter shows 64 dB(A) and this page 58 dB(A), enter 6 as the calibration offset; if this page reads higher, enter a negative number. The offset is saved in your browser for that microphone only, so a headset or USB microphone keeps its own.
Common sound levels
| Sound or guideline | Level | Source |
|---|---|---|
| Bedroom at night, for good sleep (indoor average) | 30 dB(A) | WHO Guidelines for Community Noise (1999) |
| Classroom background noise during lessons | 35 dB(A) | WHO Guidelines for Community Noise (1999) |
| Road traffic outdoors, recommended day–evening–night average (Lden) | 53 dB | WHO Environmental Noise Guidelines for the European Region (2018) |
| Normal conversation | 60–70 dB(A) | NIDCD (U.S. National Institutes of Health) |
| Long exposure unlikely to cause hearing loss | 70 dB(A) or below | NIDCD |
| Movie theater | 74–104 dB(A) | NIDCD |
| Motorcycles and dirt bikes | 80–110 dB(A) | NIDCD |
| Long or repeated exposure can cause hearing loss | 85 dB(A) and above | NIDCD; NIOSH limit for an 8-hour workday |
| Headphones at maximum volume, sporting events, concerts | 94–110 dB(A) | NIDCD |
| Concerts and clubs, recommended maximum (15-minute average) | 100 dB(A) | WHO Global Standard for Safe Listening Venues and Events (2022) |
| Sirens | 110–129 dB(A) | NIDCD |
| Fireworks show | 140–160 dB(A) | NIDCD |
How long is safe? The 3-dB rule
NIOSH, the U.S. occupational safety research institute, recommends at most 85 dB(A) averaged over an 8-hour workday, and halves the allowed time for every 3 dB more, because +3 dB is twice the sound energy. OSHA’s legal limit for U.S. workplaces is less strict (90 dB(A) for 8 hours, halving every 5 dB, with a hearing conservation program from 85 dB(A)). For headphones and music players, the WHO–ITU safe listening standard (H.870) sets a weekly dose equal to 80 dB(A) for 40 hours for adults and 75 dB(A) for children.
| Average level | NIOSH recommended maximum per day |
|---|---|
| 85 dBA | 8 hours |
| 88 dBA | 4 hours |
| 91 dBA | 2 hours |
| 94 dBA | 1 hour |
| 97 dBA | 30 minutes |
| 100 dBA | 15 minutes |
| 103 dBA | 7.5 minutes |
If the meter’s average stays above 85 dB(A) where you spend hours — a workshop, a club, a loud commute — use hearing protection and ask for a proper measurement. Ringing ears or muffled hearing after noise are warning signs; see a doctor or audiologist if they don’t go away.
Privacy
The microphone signal is analyzed on your device and is never recorded, uploaded or stored on a server. Only the calibration offset is kept, in your own browser. Want to check that the microphone itself works first? Use the mic test.
Frequently asked questions
Is this decibel meter accurate?
It gives a useful estimate, often within a few decibels after calibration, but phone and laptop microphones are not calibrated and their sensitivity differs from model to model. For legal or workplace measurements, use a certified Class 1 or Class 2 sound level meter.
What is dB(A)?
Decibels with the A-weighting filter from the IEC 61672 standard, which reduces low and very high frequencies roughly the way human hearing does at moderate levels. Most noise regulations and hearing-safety limits use dB(A).
Why does my reading never go below about 35 dB?
Small microphones have their own electronic noise. In a very quiet room that noise is louder than the room itself, so the meter can’t show lower levels.
Why do two phones show different numbers?
Their microphones have different sensitivity, frequency response and system gain. Calibrate each one against a sound level meter with the offset field; the offset is saved per microphone.
How loud is too loud?
NIDCD says sounds at or below 70 dB(A) are unlikely to cause hearing loss even after long exposure, while long or repeated exposure at 85 dB(A) or more can. NIOSH recommends no more than 85 dB(A) over 8 hours, halving the time for each 3 dB more.
Is the sound recorded or uploaded?
No. The browser computes the levels on your device; no audio is recorded, sent or stored. Only your calibration offset is saved, in this browser.
Last updated: October 15, 2026