About dBFS readings

dBFS (decibels relative to full scale) is the standard unit for digital audio levels. A value of 0 dBFS indicates the maximum representable level. Typical conversations measured 20–30 cm from a microphone fall between −30 and −20 dBFS.

dBSPL vs. dBFS

This meter reports dBFS (digital full scale), which measures the signal level in your device's audio processing pipeline. dB SPL (sound pressure level) measures actual acoustic pressure in the air.

Why the distinction matters: dBFS depends on your microphone's sensitivity and analog-to-digital converter (ADC) gain. To convert dBFS to dB SPL requires calibration with a known reference sound source (typically a 94 dB SPL tone at 1 kHz, the standard calibration level).

Bottom line: Treat this tool as a relative loudness indicator, not an OSHA-compliant noise dosimeter.

Microphone sensitivity guide

Smartphone microphones: Designed for voice (~60 dB SPL at 15 cm). They saturate (clip) at ~100–110 dB SPL. They're not suitable for measuring loud environments like concerts or construction sites.
Laptop/tablet mics: Similar to smartphones but often with lower signal-to-noise ratio. Good for general awareness; not for compliance measurements.
External USB mics: Vary widely. Studio mics (Shure SM7B, Blue Yeti) have higher dynamic range and can measure louder sounds more accurately.

For occupational noise monitoring, use a certified Type 1 (precision) or Type 2 (general purpose) sound level meter that meets ANSI/IEC standards.

Use cases

Room loudness check: Verify open-office noise levels, check HVAC noise complaints, ensure meeting room acoustic compliance.
Speaker output verification: Rough check of speaker volume before an event or presentation.
Environmental awareness: Compare relative loudness of different rooms or outdoor locations.
Not suitable for: OSHA noise exposure assessments, hearing conservation program compliance, legal evidence.

Privacy

All audio processing happens locally in your browser using the Web Audio API. No audio data is transmitted to any server.