Decibel Reader — Free Online Sound Level Meter
Measure sound with your browser microphone. Free, with no app or signup.
Your room, in real time.
Press Start to see the sound around you.
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.
A report becomes available after your first sample.
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.
- 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.
Real-Time Sound Level Meter
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 to Use This Decibel Reader
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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.
Sound Level Guide: What Each dB Range Means
These are approximate published sound examples, not measurements from this page. Source ranges overlap: distance, surroundings, and the particular source matter. An estimated browser reading cannot certify that a sound is safe.
| Reference range | Description | An example to picture |
|---|---|---|
| 0–40 dB | Low level | A whisper is listed at about 30 dB. |
| 40–70 dB | Everyday background | A refrigerator around 40 dB; a dishwasher around 45–65 dB. |
| 70–85 dB | Raised everyday sound | Talking at arm’s length can span about 65–80 dB. |
| 85–100 dB | High level | A lawn mower can span about 80–100 dB. |
| 100–120 dB | Very high level | A concert can span about 95–115 dB. |
| 120 dB and above | Extremely high level | A nearby emergency siren can reach the upper end of a 110–129 dB range. |
Examples: CDC — Listen Up! Protect Your Hearing. They are context, not a calibration reference. Do not approach or create a loud source to test this tool.
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.
Accuracy, Limitations & How to Calibrate
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
Safe Exposure Time by Decibel Level
There is no universal safe duration that this browser meter can calculate. The table below is an A-weighted occupational reference: NIOSH uses 85 dBA over eight hours, with duration halving for each 3 dBA increase. Our estimates are not dBA and must not be inserted into 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. This is not a personal countdown or a sleep, infant, medical, or legal standard. Read how the 3 dB rule works.
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
How accurate is an online decibel reader?
It depends on the microphone, processing, placement, and reference. This tool has no claimed acoustic accuracy tolerance. 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. Audio stays in your browser and is processed live. 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?
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.