Audio analysis
Loudness Checker
Measure your track. Understand the headroom.
What the numbers mean
Integrated loudness uses K-weighting with absolute and relative gating. Estimated true peak uses 4× interpolation; sample peak reads the decoded samples. Crest factor is peak-to-RMS, not a certified loudness-range measurement.
Spotify’s Normal setting targets −14 LUFS and can turn quieter tracks up when there is sufficient headroom. Playback varies by setting and device. Spotify’s normalization guidance.
Audio analysis runs locally. This meter is not a certified compliance test, and normalization alone does not determine sound quality.
How the loudness checker works
How it works
Drop in one WAV, MP3, FLAC, M4A, AIFF or OGG file up to 100 MB. The file is decoded at 48 kHz in your browser and measured there. Nothing is uploaded.
Integrated loudness follows the ITU-R BS.1770 method: K-weighting, then an absolute gate and a relative gate, so silence and very quiet passages do not pull the number down. True peak is estimated by 4x oversampling to catch peaks that fall between samples.
What you get
- Integrated loudness in LUFS for the whole track.
- Estimated true peak in dBTP.
- Sample peak in dBFS, read directly from the decoded samples.
- Crest factor in dB, the gap between peak and RMS level.
- Spotify Normal estimate: how much gain Spotify would apply to reach about -14 LUFS, and the level the track would play at. Turning a quiet track up is limited by its peak headroom.
You also see the duration, channel count and sample rate used for the analysis.
Good to know
- This is a measurement, not a certified compliance test.
- Crest factor is not the same as a loudness range (LRA) reading.
- The Spotify figure is a single-track estimate. Album playback, other settings and devices can differ.
- Louder is not better. A track at -9 LUFS is turned down on most services, and its peaks come down with it.
Questions
- What LUFS should my song be for Spotify?
- Spotify's Normal setting plays tracks at about -14 LUFS. A louder master is turned down to that level. A quieter master is turned up only as far as its peak headroom allows. Many releases sit between -14 and -9 LUFS; pick the level that sounds right for the song.
- What is the difference between true peak and sample peak?
- Sample peak is the highest value in the file. True peak estimates the highest point of the waveform between samples, which can be higher. Converting to MP3 or AAC can push those peaks over 0 dB, so many engineers keep true peak at -1 dBTP or lower.
- Is my track uploaded?
- No. The file is decoded and measured in your browser and does not leave your device.
- Which file types and sizes work?
- WAV, MP3, FLAC, M4A, AIFF and OGG, one file at a time, up to 100 MB.