How to Calibrate a Browser Decibel Meter
Calibration here means one thing: adding a fixed dB offset measured against a reference you trust.
Last materially reviewed: 2026-09-16
Why calibration matters
Every consumer microphone has different gain, so the same sound produces different raw readings on different devices. Until you measure that difference against a known reference, the meter can only show microphone input strength — never an environmental sound level in dBA.
What you need
- A stable reference of known level: a calibrated sound level meter side by side, or an acoustic calibrator tone at a stated level (commonly 94 dB).
- The same device, microphone, position and browser settings you will measure with later.
- Matching frequency weighting (A, C or Z) and time response (Fast or Slow) on both sides.
How to calibrate
- Place the device where you will measure — stable surface, ear height, mic port uncovered, away from wind.
- Expose it to the stable reference and let the display settle for several seconds.
- Read the uncalibrated value on this site and enter the difference (reference − shown) as the offset in Customize → Calibration.
- Confirm the status badge changes from “Uncalibrated” to “Calibrated” and re-check against the reference.
Saving device-specific profiles
The offset is stored in this browser for the current microphone and weighting setup. It auto-applies only when the same setup is detected; change the input device and the profile stops applying rather than silently producing wrong numbers. Reset any time to return to the raw estimate.
When profiles become incompatible
- You switch microphones, headsets or USB inputs.
- You change weighting (A/C/Z) or response (Fast/Slow).
- The browser or OS changes gain, enables AGC, or updates audio processing.
- You measure in very different acoustics (near-field vs room) — re-check against a reference.
Common calibration mistakes
- Calibrating with music or speech instead of a stable tone — levels jump too much to read.
- Holding the phone in your hand while calibrating, then measuring on a table.
- Mixing weightings: calibrating in dBA, then comparing in dBC.
- Assuming one phone's offset transfers to another device.
- Treating a calibrated browser as a certified meter — it remains an estimate (see browser measurement accuracy).