"Positive" adds an offset to raw dBFS. "Negative" shows the actual dBFS value (usually below 0).
Applies standard frequency weighting using FFT analysis to better reflect perceived loudness (dBA) or low-frequency content (dBC).
How often the display and graph update. Faster rates use slightly more CPU for UI rendering.
How long the highest measured peak reading is displayed before potentially resetting.
Adjusts the displayed reading (+/- dB) for relative comparison.
Visual representation of the sound level or frequency content.
Accuracy Disclaimer: This tool measures relative sound levels in dBFS (decibels relative to full scale), the digital audio level captured by the microphone. Frequency weighting (dBA/dBC) is now applied using standard curves and FFT analysis for better relative accuracy, but it does NOT measure absolute dB SPL (sound pressure level) without external calibration. Readings remain highly dependent on the specific microphone, device gain settings, distance, and potential OS/browser audio processing. Use for general level indication and relative comparisons, not precise measurements. Disable system audio enhancements for best results.
Info & Troubleshooting
About this meter
An A-, C- or Z-weighted sound level meter that runs entirely in your browser via the Web Audio API. All audio processing is local — nothing is uploaded or recorded. Once calibrated against a known reference, the reading is dB SPL (sound pressure level).
Calibrate before you trust the number
Out of the box a smartphone or laptop can read 5–15 dB off a Class 2 reference. The calibration walkthrough takes about five minutes and brings agreement to within ±2 dB for everyday sources.
If your readings look off
Disable system audio enhancements (AGC, noise suppression, echo cancellation) in your OS sound settings.
Place the device on a soft cloth with the mic facing the source — don't hold it.
Use A-weighting for ambient and workplace noise; switch to C only when bass dominates (concerts, subwoofers, thunder).
Outdoors, fit a foam windscreen over the mic — even a light breeze reads as 60–80 dBA.
Common issues
No microphone detected
Click the lock icon in the address bar, reset microphone permission for this site, then refresh. On laptops, check for a hardware mic-mute switch on the function row.
Stuck at 0 dB or unusually low
A Bluetooth headset or USB microphone may have hijacked the input. Disconnect it, or change the input device in your operating system's sound settings.
Above ~95 dBA underreports
Most consumer mics clip between 95 and 110 dB SPL. Use a dedicated Class 2 sound level meter (IEC 61672-1) for loud concerts, machinery, or compliance work.
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