Online dB Meter

For audio files, yes: sample peak, true peak and RMS are exact digital measurements of the decoded file, and our checks match ffmpeg to within 0.1 dB. The live mic reading is an uncalibrated estimate, because phone and laptop mics do not report real sound pressure. Set the calibration offset against a real SPL meter if you need a closer number.

dBFS (decibels relative to full scale) measures digital level, where 0 dBFS is the loudest sample a file can hold. dBTP (true peak) is the same scale measured with 4× oversampling, so it also catches peaks that fall between samples. dB SPL is acoustic sound pressure in a room, which only a calibrated microphone can measure.

Most streaming platforms recommend a true peak of −1 dBTP or lower so that MP3 and AAC encoding does not clip. Very loud masters often need −2 dBTP. A true-peak limiter on your master bus is the usual way to hold this.

RMS is the average power of the signal, which tracks how loud it feels better than peaks do. Crest factor is peak minus RMS: a big number means punchy, dynamic audio, while a small one (under about 8 dB) usually means heavy limiting.

No. Files and mic audio are processed by JavaScript in your own browser and never leave your device.