Sound Decibel Meter
Not measuringMeasuringStoppedMicrophone blockedNo microphone found
--
dBAdBC
The microphone is blocked for this site. To allow it:
- Tap the lock or settings icon next to the address.
- Set Microphone to Allow (on iPhone: Settings, Safari, Microphone).
- Reload the page and press Start.
No microphone could be opened. Connect one, close other apps using it, then press Start again.
Microphone at its limit: the real level is higher
Your browser may still be processing the sound, so readings can be off.
- Min
- --
- Avg (Leq)
- --
- Max
- --
Audio stays on your device.
Decibel levels, 10 to 140 dB
- 10 dBRustling leavesHow loud is 10 dB?
- 20 dBA whisperHow loud is 20 dB?
- 30 dBA quiet bedroom at nightHow loud is 30 dB?
- 40 dBA quiet libraryHow loud is 40 dB?
- 50 dBA quiet office or light rainHow loud is 50 dB?
- 60 dBNormal conversationHow loud is 60 dB?
- 70 dBA busy street or a vacuum cleanerHow loud is 70 dB?
- 80 dBA loud restaurant or an alarm clockHow loud is 80 dB?
- 85 dBHeavy city trafficHearing damage lineHow loud is 85 dB?
- 90 dBA lawn mower or a subway trainHow loud is 90 dB?
- 100 dBA chainsaw or a nightclubHow loud is 100 dB?
- 110 dBA rock concertHow loud is 110 dB?
- 120 dBAn ambulance sirenHow loud is 120 dB?
- 130 dBA jackhammer up closeHow loud is 130 dB?
- 140 dBA jet takeoff or a gunshot at close rangeHow loud is 140 dB?
How to measure accurately
Measure for 30 to 60 seconds and read the average (Leq), not the reading from a single moment. Measure while the room is in its usual state, so the reading shows how it really sounds.
- Put the phone on a stand, or hold it in your hand with the microphone uncovered. The microphone is usually on the bottom edge.
- Keep the screen on. On phones, the browser stops the microphone when the screen locks.
- Leave the meter on its default, dBA, which follows how most people hear everyday noise. Switch to dBC only if you care most about bass or rumble.
- Tap Start and stand where the sound is.
- Wait 30 to 60 seconds, then read Avg (Leq), the average level over that time.
Good practice
- Hold the phone at ear height, away from your body.
- Stay away from reflecting walls, which push levels up.
- Avoid wind, and do not touch the phone while it measures.
- Watch for the clipping warning. When it appears, the real level is higher than shown.
What the numbers on the meter mean
dB (decibel)
The unit of sound level. The scale is logarithmic: +10 dB sounds about twice as loud and is ten times the sound energy.
dBA
A decibel reading weighted to match human hearing, which is less sensitive to very low and very high pitches. It is the standard for everyday noise and for hearing-safety limits, and it is the meter's default.
dBC
An almost flat weighting that also counts low, bassy sound such as music, engines and rumble. If dBC reads much higher than dBA, the sound has a lot of bass.
Min and Max
The quietest and the loudest level since you pressed Start.
Avg (Leq)
The average level over the time you measured. It is an energy average, so loud moments count more than quiet ones. Health limits such as 85 dBA for 8 hours use this number.
Live reading
The big number, updated several times a second. It is good for seeing changes, not for judging a room.
What your reading means
Your reading is a level in dBA, and each band below gives a rough sense of what the sound is like.
| Level | Band | What it feels like |
|---|---|---|
| Under 40 | Quiet | Calm. Background sound is hard to notice. |
| 40 to 60 | Moderate | Normal conversation is easy. A typical room with people in it. |
| 60 to 85 | Loud | Busy and noticeable. Talking takes more effort near the top of the band. |
| 85 to 100 | Very loud | You may need to shout to be heard at arm's length. Limit time here. |
| Above 100 | Dangerous | Hearing damage is possible in minutes. At 100 dBA, the NIOSH safe time is about 15 minutes. |
Decibels are logarithmic. +10 dB sounds roughly twice as loud, and +3 dB is double the sound energy.
How accurate is a phone?
A phone is useful for comparing rooms and finding loud hours, but it is not a calibrated sound level meter. No phone app meets the IEC 61672 Class 1 or Class 2 standard on its own. Compare readings from the same phone and spot, which is more reliable than comparing across different phones.
Below about 25 to 35 dB
Quiet sounds
What to expect
Near the microphone's noise floor, so readings are unreliable.
65 to 95 dBA
Most everyday sounds
What to expect
The best iPhone apps read within about 2 dBA of a professional reference meter.
Above about 95 to 110 dB
Very loud sounds
What to expect
Near the microphone's ceiling. Many Android phones read low above 90 dB.
Phone and laptop microphones are built for voices, not measurement. Browsers also add voice processing, such as echo cancellation, noise suppression, and automatic gain. That processing distorts levels, so this meter turns it off and warns you if the browser keeps it on.
If the microphone hits its ceiling, the meter shows a clipping warning. The real level is higher than the number shown.
In NIOSH tests, a phone app with an external calibrated microphone came within about 1 dBA. This site does not support external microphones yet.
Calibrate your meter
Calibrate only when you have a reference meter and need readings closer to it. Without calibration, your phone still shows useful differences between rooms.
- Place your phone and the reference meter side by side, at the same spot and height.
- Measure the same sound with both for 30 to 60 seconds, and note each Leq.
- Subtract the phone's Leq from the reference Leq to find the difference.
- Enter that difference as the Calibration Offset. Add or subtract dB so your device matches the reference.
A 94 dB / 1 kHz acoustic calibrator is another reference. It produces a known level, so you can check the reading against 94 dB.
The offset is remembered in this browser only, so set it again on each device you use.
How long is safe?
The NIOSH recommended limit is 85 dBA averaged over 8 hours, and every +3 dB halves the safe time.
| Level | Safe time 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 | about 7.5 minutes |
| 106 dBA | about 4 minutes |
| 109 dBA | about 2 minutes |
| 112 dBA | about 1 minute |
OSHA, the US workplace law, uses 90 dBA for 8 hours with a 5 dB exchange rate, and an action level of 85 dBA. NIOSH's limit is the stricter guideline.
Watch for these warning signs
- You must shout to be heard at arm's length.
- You have ringing in your ears or muffled hearing afterward.
Record noise over time
A single reading shows one moment. Most noise problems, such as neighbor noise at night, a loud work shift, or a bedroom that is too noisy to sleep in, show up as a pattern over hours.
The Noise Meter logs one level per second for 15 minutes to 8 hours, or with no limit. It marks the periods above a threshold you choose, and summarizes the log with Leq, L10, L90, and the maximum. It stores levels only, never audio, and you can download each log as CSV.
Typical places and targets
Each place below has a level to aim for or a level to watch. Treat them as guides, not rules. Compare a noise log's Leq with the target, not a single reading.
Bedroom at night
under 30 dBA
the WHO guideline for good sleep. Measure with the windows as you usually keep them.
How loud is 30 dB?Home by day
about 40 dBA
a quiet home. Measure at the time of day you care about, not just once.
How loud is 40 dB?Office
about 50 dBA
an open-plan office. Conversation is about 60 dB. Measure during a normal workday.
How loud is 50 dB?Classroom
about 35 dBA
the background many guidelines aim for in an empty classroom. Measure the empty room first, then again with students in it.
How loud is 35 dB?Concert or headphones
100 dB or more
concerts and clubs, safe for about 15 minutes by NIOSH. Use ear protection and take breaks.
How loud is 100 dB?Workplace
85 dBA or more
long periods at this level are a reason to act. Talk to your employer about a proper noise assessment.
How loud is 85 dB?
Your audio stays on your device
Your audio is analyzed on your device and is never uploaded. There is no account.
- Processed The meter analyzes the microphone signal in your browser, on your device.
- Stored Noise logs keep one level per second, never audio. The last 10 logs are kept in this browser.
- Not uploaded Nothing leaves your device, and there is no upload step.
- Deleting Remove a log on the Noise Meter page, or clear this site's data in your browser to remove them all.
Common questions
Is this a real decibel meter?
It measures sound level in dB with your device's microphone. The microphone is built for voices, so the result is an estimate, not a certified measurement.
Why is my reading different from another app?
Apps differ in microphone, voice processing, weighting, and calibration. To compare them, measure the same sound with both, or check against a reference meter.
Why does it not read below about 25 dB?
Every built-in microphone has a noise floor, roughly 25 to 35 dB. Readings near that floor are unreliable, so treat very low numbers as estimates.
Does it work on iPhone and Android?
Yes, it runs in the phone's browser. Accuracy depends on the phone: in NIOSH tests, the best iPhone apps read within about 2 dBA of a reference meter, and many Android phones read low above 90 dB.
Do I need to install anything?
No. It runs in your browser, and you do not need an account.
Can I use it as evidence for a noise complaint?
Not on its own. A noise log describes a pattern well, but it is not certified evidence, and local rules and authorities decide.
Why does the reading stop when my screen locks?
On phones, the browser stops the microphone when the screen locks. Keep the screen on while you measure. Noise logs mark these gaps.
Is dB or dBA what I want?
For room and workplace noise, use dBA, the standard for environmental and workplace noise. Use dBC when bass or low rumble matters, such as engines or music.