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Uncalibrated input estimate: the displayed numbers, colors, and sound-level labels cannot establish hearing safety or actual dB SPL.

🎚️ Decibel Meter

Measure sound level (dB) in real time using your device's microphone.

Requires microphone access — audio is analyzed locally and never uploaded.

–dB
—
04080120 dB

⚠️ Approximate only — phone and laptop microphones are not calibrated. Use for relative comparison, not for safety or legal measurements.

📏 Reference points
  • 20–30 dB — whisper / very quiet room
  • 40–60 dB — normal conversation
  • 60–80 dB — busy street / vacuum cleaner
  • 80–100 dB — loud music / power tools
  • 100+ dB — rock concert / jet engine (hearing damage risk)

Use the microphone reading for controlled comparisons

The tool computes the microphone signal's RMS level in dBFS and applies a fixed display offset. It has no device-specific microphone calibration or acoustic reference measurement.

A repeatable check

  1. Start the microphone and keep the same device, input gain, orientation, and position for every comparison.
  2. Observe the reading with a sound source off, then on. Repeat the comparison without moving or touching the microphone.
  3. Use the direction and consistency of the change as a clue, then stop microphone access when finished.

What the result suggests

Two phones give different readings
Their microphone sensitivity and processing differ. Do not average the numbers into a supposed calibrated SPL value.
The reading settles despite changing sound
Automatic gain control or noise suppression may be modifying the input. Check available system input processing and repeat with the same settings.

What this cannot establish

A fixed offset does not convert an unknown microphone into a calibrated sound-level meter. The reading cannot establish dBA, noise exposure, hearing safety, or compliance with a legal limit.

Testing methods and limitations

Frequently Asked Questions

What does the displayed number represent?

The code calculates the digital microphone signal's RMS level, converts it to dBFS, and adds a fixed offset of 90. That offset is not a calibration for your microphone, and the tool does not apply A-weighting.

Can this tell me whether my headphones or room are safe?

No. It does not measure calibrated sound pressure at your ear or cumulative exposure. A green label or a low displayed number is not evidence of a safe listening level. Use an appropriate calibrated measurement method when the absolute level matters.

How can I make a useful comparison?

Keep the microphone, input settings, distance, and orientation unchanged. Compare a source off and on several times. Automatic gain control or noise suppression can change the relationship between input and displayed level, so even relative comparisons have limits.