Decibel Meter — Free, Browser-Based Sound Level Meter
Measure approximate sound levels with your device microphone: a live dB readout with color-coded bar, peak hold, session average, and a rolling 60-second chart. A calibration slider lets you align readings with a reference meter. Audio is analyzed in real time and never recorded or uploaded.
Private by design. Microphone audio is analyzed in real time in your browser to compute a loudness number and immediately discarded — nothing is recorded or uploaded.
How to measure sound level (dB) with your microphone
- Start measuring. Click Start measuring and allow microphone access when the browser asks. The meter begins updating immediately.
- Read the level. The big number is the approximate dB SPL right now. Green means comfortable, orange is loud, red (85 dB+) is hearing-damage territory over sustained exposure.
- Watch peak, average, and the chart. Peak hold captures the loudest moment, the average summarizes the session, and the chart shows the last 60 seconds of levels.
- Calibrate if you can. Browser mics measure relative loudness, not absolute pressure. If you have a real SPL meter or a calibrated phone app, adjust the offset slider until readings match.
Use Cases
Frequently Asked Questions
Is my audio recorded or uploaded?
No. The microphone signal is analyzed in real time to compute a loudness number and then discarded — nothing is recorded, stored, or sent to a server.
How accurate is a browser decibel meter?
It is an estimate, typically within ±5–10 dB after calibration. Consumer microphones, browser processing, and auto-gain quirks all add error — treat readings as indicative, not certified.
What does the calibration offset do?
Web audio reports dBFS (relative to digital full scale), not absolute sound pressure. The offset (default +90) maps dBFS to an approximate dB SPL; tune it against a reference meter for your specific device.
What sound level is dangerous?
NIOSH recommends keeping average exposure under 85 dB for an 8-hour day; every 3 dB above that halves the safe time. 100 dB is safe for only about 15 minutes.
Why does the meter read low in a loud room?
Some browsers apply automatic gain control or noise suppression to mic input. This tool requests raw input where possible, but device-level processing can still compress loud sounds.
Can I use this for legal or workplace noise complaints?
No. It is not a certified Class 1/Class 2 sound level meter. For regulatory or occupational measurements, use calibrated hardware — this tool is for awareness and rough checks.
Decibel reference — from library quiet to pain threshold
Decibels are logarithmic: every +10 dB is roughly twice as loud to the ear and ten times the sound energy. That is why the jump from 85 to 95 dB matters far more than it looks.
| Level | Typical source | Safe exposure (NIOSH) |
|---|---|---|
| 30 dB | Quiet library, whisper | Unlimited |
| 60 dB | Normal conversation | Unlimited |
| 70 dB | Vacuum cleaner, busy street | Unlimited (annoyance, not damage) |
| 85 dB | Heavy traffic, blender | 8 hours |
| 95 dB | Motorcycle, subway platform | ~47 minutes |
| 100 dB | Nightclub, sporting event | ~15 minutes |
| 110 dB | Loud concert, chainsaw | ~2 minutes |
| 120 dB | Rock concert front row, siren | Immediate risk — pain threshold |
- Exposure limits follow the NIOSH 3-dB exchange rate: each 3 dB increase halves the recommended maximum daily exposure time.
- Readings here are A-weighted approximations at best — microphone frequency response varies, so treat the meter as a guide rather than an instrument.