Decibel Meter
Measure ambient sound levels in real time using your device's microphone. Displays estimated dB SPL with a live bar meter, peak hold needle, and session statistics. No audio is recorded.
Measure ambient sound levels in real time using your device's microphone.
Grant microphone access to begin. No audio is ever recorded or transmitted.
Decibel Meter uses your device's microphone to measure ambient sound levels in real time. The live bar meter and large digital readout update several times per second, a peak-hold needle marks the recent maximum, and session statistics track the highest and lowest levels recorded since you started listening — all without recording or transmitting any audio.
How to Use
Click Start Microphone and grant permission when your browser asks. The meter activates immediately and begins displaying the current level. Normal conversation registers around 55–65 dB, a quiet office sits near 40–50 dB, and loud music or traffic can push past 80 dB. Click Stop when finished — the microphone is released instantly.
Understanding the Reading
The values shown are estimates. The tool calculates the RMS (root mean square) level of the raw audio samples captured by your microphone and applies a fixed calibration offset to approximate real-world dB SPL. Actual accuracy depends on your device's microphone quality and factory calibration. Do not use these readings for professional noise compliance or occupational health assessments — use a certified sound level meter for that purpose.
Noise Level Reference
| Range | Label | Typical Source |
|---|---|---|
| 0–35 dB | Quiet | Whisper, library, recording studio |
| 35–55 dB | Moderate | Normal speech, quiet office |
| 55–70 dB | Loud | Busy street, restaurant, TV |
| 70–85 dB | Very Loud | Vacuum cleaner, busy traffic |
| 85+ dB | Dangerous | Power tools, concerts, machinery |
Prolonged exposure above 85 dB can cause permanent hearing damage.
Peak Hold & Session Stats
The white needle on the bar holds the recent peak level for approximately 1.5 seconds before slowly decaying. The Session Peak and Session Min values in the stats bar record the extremes for the entire active session — useful for identifying noise spikes or measuring the quietest moment in the room.
Privacy
The microphone stream is processed entirely within your browser using the Web Audio API. No audio data is recorded, stored, or transmitted to any server. The microphone is active only while the meter is running — clicking Stop releases the device immediately and no further access occurs.
FAQ
Does the reading match a professional sound level meter?
Not exactly. Consumer device microphones vary widely in frequency response and sensitivity. The readings are useful for rough comparisons and relative measurements, but should not replace a calibrated instrument for professional or regulatory purposes.
Why does the browser ask for microphone permission?
The Web Audio API requires explicit user permission to access the microphone. This is a browser security requirement — no audio is processed until you grant access, and access is released the moment you click Stop.
Does this work on mobile phones?
Yes. It works on any device with a microphone and a browser that supports the Web Audio API, including iOS Safari (14+) and Android Chrome.
What is dB SPL?
dB SPL (Sound Pressure Level) measures the pressure of a sound wave relative to the threshold of human hearing (20 µPa). 0 dB SPL is the quietest detectable sound; 85 dB SPL is the occupational safety threshold for prolonged exposure; 120 dB SPL is roughly the pain threshold.
Does it record my audio?
No. The Web Audio API processes audio data in memory frame by frame. No recording is made at any point, and no audio or measurement data ever leaves your device.