Free LUFS meter: Know how loud your track is before you release it.
This free LUFS meter reads integrated loudness, true peak and loudness range, and explains each in plain words.
Or measure a personal mastering sample
Real before/after files from the samples library, mastered by hand — not automatic-mastering output. Each is fetched from this site, then decoded and measured here exactly like your own file.
What you get
- See what Spotify will do to it. How far its published normalisation turns each track down or up.
- Catch peaks that clip after encoding. True peak is read between samples, where a plain peak meter cannot see.
- Check a whole record at once. Up to 20 files in one session; copy the readings or download a CSV.
- Keep unreleased music private. Measured in your browser; nothing is uploaded and no account is needed.
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Audio level through the track
Measured peak and RMS levels. This waveform shows amplitude, not a loudness-over-time curve.
Master this file.
Master the same file against a delivery target, and hear it at its mastered loudness against what you just measured. The preview is free and full length.
LUFS · dBTP · LU
What LUFS, true peak and LRA mean
- Integrated loudnessLUFS · how loud the whole track is
- One number for the whole track, weighted the way hearing works rather than the way a meter does, with the silence between sections gated out. It is the figure Spotify uses to decide how far to turn your track up or down, which is why it is the number worth aiming at.
- True peakdBTP · the highest level, including between samples
- A digital file only stores levels at each sample. Reconstructing the waveform for playback — or encoding it to MP3 or AAC — produces peaks between those samples, and those are what actually clip. A track whose highest sample reads 0.0 dBFS can still distort on a phone. A decibel of true-peak headroom usually prevents that at high bitrates; Spotify and SoundCloud ask for two above −14 LUFS.
- Loudness rangeLU · the distance between the quiet parts and the loud parts
- How much distance is left between the quiet parts and the loud parts across the whole track. Very low numbers usually mean heavy limiting. Very high numbers can mean the arrangement has not been controlled yet. There is no correct value.
How this tool measures
Integrated loudness follows ITU-R BS.1770 (revision 4, whose stereo measurement revision 5 kept): K-weighting, 400 ms blocks at 75% overlap, an absolute gate at −70 LUFS and a relative gate 10 LU below the loudness of the blocks that passed it. Loudness range follows EBU Tech 3342: 3-second windows read ten times a second, a 20 LU relative gate, and the spread between the 10th and 95th percentiles. It passes the four synthetic cases of the standard’s six minimum-requirement test signals.
True peak is oversampled four times, which is how BS.1770 defines it for a 48 kHz signal, through a 32-tap windowed-sinc filter per phase rather than the standard’s own filter table — so treat it as a headroom check rather than a compliance certificate. Compared with ffmpeg’s ebur128 meter on five 48 kHz test signals, including hard-clipped noise that peaks 7.1 dB between samples, this page read within 0.25 LU on integrated loudness and loudness range and matched true peak to one decimal.
Files are decoded by your browser at 48 kHz, so a 44.1 kHz file is resampled before measurement. Which formats decode at all is your browser’s decision: WAV and MP3 work in the major browsers; FLAC, AIFF and M4A depend on which one you use.
Questions
Questions about the checker
Does my file get uploaded?
No. The measurement runs in your browser and the file never leaves your computer. Close the tab and nothing is kept.
Which numbers does this LUFS meter report?
Integrated loudness in LUFS, true peak in dBTP, and loudness range in LU — the same three the master pages report.
Is this the same measurement the mastering uses?
For loudness and range, yes — the same BS.1770 and EBU Tech 3342 methods, and the numbers are directly comparable. True peak is oversampled four times here, as the standard defines it, using a windowed-sinc filter rather than the standard’s own filter table — close enough to read as a headroom check, not as a compliance certificate.
What number should I be aiming for?
There is no single right answer, which is why the site publishes what each platform actually states rather than an industry rule of thumb. Most of them publish nothing at all.
Why is my true peak above zero?
A sample peak under full scale can still overshoot between samples, and a lossy encoder adds more of that on decode. A peak meter does not show it.
What a LUFS meter tells you.
Integrated LUFS describes loudness across the whole file. True peak and loudness range add context; they do not tell you whether the song sounds good. Read the results, listen to the track and use level-matched comparison when judging two versions.
