Decibel Reader — Free Online Sound Level Meter
Get live estimated sound levels from your browser microphone. Free; no app or signup.
Microphone unavailable
Microphone permission help
Chrome: open the site controls beside the address, then allow Microphone. Safari on Mac: use Safari → Settings → Websites → Microphone. On iPhone or iPad, open the website settings in Safari’s page menu and check Microphone. Also check the browser’s microphone access in your device privacy settings. Labels vary by OS version. Return here and try again.
Sound level
Estimated dB · last 30sReference lines use Estimated dB, not measured dBA safety limits.
Frequency spectrum
Digital levelBands at or below −80 dBFS are outside this view. Bars show total digital power per band. Wider bands can contain more noise. The right edge is the range limit; the peak is not a voice pitch measurement.
Audio stays in your browser. Nothing is recorded or uploaded.
How accurate is this?Settings & calibrationOptional
The default offset is a display estimate, not a sound pressure calibration. A reference meter can align this device at one sound level. Read the method.
Color bands describe estimated loudness, not safety. The circles respond to digital microphone input.
- Calibration status
- Uncalibrated
- Raw digital level
- — dBFS
- Total display offset
- +94.0 dB
Changing an offset starts fresh statistics. Only the offset preference is saved on this device.
Align with a reference instrument
- Use a calibrated sound level meter and a steady sound source.
- Place both microphones together, facing the same direction.
- Start measuring here, then collect 10 seconds. Enter the reference meter’s average for the same interval. Keep its weighting and settings in mind: this browser reader is unweighted.
One-point alignment cannot correct frequency response or make this a certified meter.
No reference meter? Check a relative baseline
Leave the device still in a quiet room for 10 seconds. This records a digital baseline for comparisons on the same device; it does not discover the room’s real SPL or change your offset.
Sound Levels & Their Effects
Illustrative bands, not health thresholds. Real levels vary with distance and may span several bands.
When can sound harm hearing?
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70 dBA or lower
Unlikely to cause hearing loss, even with long exposure.
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85 dBA or higher
Long or repeated exposure can cause hearing loss. Reduce exposure and protect your hearing.
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Sudden, very loud sound
A short burst, such as an explosion, can damage hearing immediately.
Loudness, duration and distance all matter. These refer to measured dBA, not this browser’s Estimated dB. NIDCD — Noise and hearing.
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Under 20 dBGentle breathingAbout 10 dBVery quiet; heard in a quiet room.
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20–30 dBRustling leavesAbout 20 dBQuiet, gentle background sound.
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30–40 dBSoft whisperAbout 30 dBSoft speech at close range.
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40–50 dBFridge humAbout 40 dBLow, steady background noise.
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50–60 dBHome backgroundAbout 50 dBNoticeable everyday background sound.
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60–70 dBEveryday conversationAbout 60 dBOrdinary speech; easy to hear nearby.
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70–80 dBVacuum cleanerAbout 70 dBLouder background noise; take breaks.
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80–90 dBCity trafficAbout 85 dB inside a carLoud surroundings; reduce time near the noise.
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90–100 dBPassing motorcycleExample range: 80–110 dBVery loud; limit exposure and protect your hearing.
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100–110 dBPower drillAbout 100 dBUse hearing protection around loud tools.
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110–120 dBRock concertExample range: 95–115 dBProtect your hearing; move away from speakers.
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120+ dBEmergency sirenExample range: 110–129 dB nearbyAvoid close exposure; move away from the source.
Listening guidance:
Loudness, duration and distance all matter. Browser estimates are not certified SPL or dBA and cannot assess your hearing risk.
Occupational noise exposure reference
For measured A-weighted sound (dBA), NIOSH recommends 85 dBA over an eight-hour workday. Each 3 dB increase halves the corresponding daily duration. This is an occupational reference, not a guarantee of safety or a personal countdown. Do not use this browser’s Estimated dB in this table.
| Measured A-weighted level | Duration |
|---|---|
| 85 dBA | 8 hours |
| 88 dBA | 4 hours |
| 91 dBA | 2 hours |
| 94 dBA | 1 hour |
| 97 dBA | 30 minutes |
| 100 dBA | 15 minutes |
Source: NIOSH — Understand Noise Exposure. These durations are not sleep, infant, medical or legal standards. How the 3 dB rule works.
What is an online decibel reader?
This free decibel reader turns your browser microphone signal into a live estimate. Use it to observe changes in a room, compare two fan settings, or see when a background sound rises. No app or account is needed.
The display is Estimated dB. It is not a certified sound-pressure-level measurement or an A-weighted dBA reading. Your microphone and its processing affect the number; comparing repeatable conditions on the same device is the most useful starting point.
How do I measure room noise online?
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Start and allow the microphone
Press Start Measuring and approve the browser permission. Keep the microphone opening clear and put the device on a stable surface.
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Observe a representative interval
Try 30–60 seconds for a steady sound. Keep the position and settings the same when comparing conditions. A short quiet interval can miss an intermittent source.
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Stop, compare, and save
Read Average alongside Min, Max, and the recent history. Stop to release the microphone. Save a local PNG report or use the print view to save a PDF.
Decibel Reader vs. Sound Level Meter: What’s the Difference?
“Decibel reader” is a common way to describe a tool that shows a sound-level number. A professional sound level meter is a defined measurement instrument, with a microphone, calibration, frequency weighting, and response chosen for the task.
This browser tool reads a digital microphone signal and adds an explicit display offset. It is convenient for informal comparisons. For traceable sound pressure, legal limits, or occupational exposure, use an appropriate calibrated instrument and procedure.
Understand Estimated dB and the raw dBFS value · Compare dB, dBA, dBC and dBFS · Read the live frequency spectrum
Can I calibrate an online decibel reader?
Microphone sensitivity, input gain, frequency response, automatic processing, and placement can all change the result. We request processing to be disabled, but browsers and devices may not honor every setting. There is no claimed acoustic error tolerance for this tool.
To align the display, place it near a reference instrument, use a stable ordinary source, take the 10-second reference sample in Settings, and enter the reference reading from that interval. Recheck after changing the setup. One offset cannot correct every frequency or signal level.
Without a reference, a quiet-room check is only a relative baseline. An unknown quiet room cannot provide a known SPL calibration.
Read the measurement method · Review accuracy limits · Follow reference alignment steps
Common Uses: Home, Office, Audio & Sleep
At home
Compare a window open and closed, or two appliance settings, with the device in the same position.
At a desk
Observe when a fan or nearby equipment changes the background. Repeat before-and-after conditions.
For an audio setup
Compare relative changes in an ordinary listening setup. A device mic does not certify speaker output or measure sound inside headphones.
In a bedroom
Compare a noise source at the same location and time conditions. A short reading does not establish sleep suitability or a health threshold.
Frequently Asked Questions
Is Decibel Reader free, and do I need an account?
Yes. Decibel Reader is free to use, including local PNG reports and the print/PDF view. No account, subscription, or app download is required. You need a browser with microphone access and Web Audio support.
Does this online meter measure dBA or certified sound pressure?
No. Decibel Reader displays Estimated dB from a digital microphone signal plus a display offset. It does not apply A weighting or provide certified SPL readings. Reference alignment changes the offset; it does not certify the microphone. See accuracy and limitations.
How accurate is an online decibel reader?
Decibel Reader has no verified acoustic accuracy tolerance. The result depends on the microphone, processing, placement, and reference. Use it for informal comparisons, and read the accuracy limits before interpreting an absolute number.
Why does the site need microphone permission?
The browser needs your permission to provide a live input signal. If access is denied, allow the microphone in the browser’s site permissions and check your operating system’s microphone privacy settings, then retry. Browser and device settings differ.
Can I use it on a phone?
Yes, if your mobile browser supports microphone capture and Web Audio on this HTTPS page. Keep the microphone clear and the page visible. Locking the device or moving the browser to the background may interrupt measurement.
Is my audio recorded or uploaded?
No. Decibel Reader does not record, upload, or retain audio; it processes the microphone signal live in your browser. The page retains derived levels for the current session and your chosen offset on this device, not an audio recording. Read the privacy explanation.
Can I calibrate it in a quiet room?
No. A quiet-room sample can establish a relative baseline, not a known sound pressure. Absolute display alignment requires a reference instrument and a stable shared condition. Reference alignment still does not certify the device.
Why is the raw dBFS reading negative?
dBFS compares digital amplitude with full scale. A negative value means the signal is below that digital reference, not that the sound is negative. The main Estimated dB display adds an explicit offset.
What is included in a saved report?
The report includes the time, sampled duration, Min/Average/Max, a full-session overview curve, offset, and accuracy status. PNG and printing are local. The live chart shows the latest 30 seconds; long report curves use an energy-averaged overview while statistics retain all valid samples.
Why is my reading unusually high, low, or flat?
Check the selected input, microphone opening, browser processing, and saved offset. Another device or changed input gain can produce a different number. Reset the offset and compare a repeatable condition; use a reference instrument when the absolute level matters.