LUFS meter

Updated October 20, 2026 by madebykamal

LUFS (loudness units relative to full scale) measure how loud audio sounds across its whole length, using the ITU-R BS.1770 method. Choose or drop a file below to get its integrated loudness, true peak, short-term and momentary maximums and loudness range, measured in your browser with nothing uploaded, then see how Spotify's default level of -14 LUFS would change it.

What each number means

Integrated loudness is the one number streaming services and broadcasters normalize to. The others explain how the track gets there.

• Integrated loudness (LUFS): the average loudness of the whole file, after gating out silence and very quiet passages.
• True peak (dBTP): the highest level of the waveform including the peaks between samples, which a converter or a lossy encoder can reach.
• Short-term max (LUFS): the loudest 3 seconds.
• Momentary max (LUFS): the loudest 400 milliseconds.
• Loudness range (LU): how much the loudness moves across the track, from the quieter passages to the loud ones, leaving out the extremes.
• Sample peak (dBFS): the highest single sample, which can sit below the true peak.

BPM, Key and Loudness: Quint

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How Spotify normalizes loudness

Spotify for Artists says Spotify adjusts tracks to -14 dB LUFS, measured to ITU-R BS.1770. A master louder than that gets negative gain, so it plays quieter. A softer master gets positive gain, but Spotify considers the track's headroom and leaves 1 dB of headroom for lossy encodings, so a quiet track with high peaks may stop short of -14 LUFS.

Spotify normalizes an album as a whole, so the gain does not change between its tracks. Premium listeners can also pick a Loud level of -11 LUFS, with a limiter at -1 dB, or a Quiet level of -19 LUFS.

For true peak, Spotify advises staying below -1 dBTP, and below -2 dBTP if the master is louder than -14 LUFS integrated, to avoid distortion when the file is transcoded. The meter above checks your file against both.

Apple Music Sound Check

Apple's Apple Digital Masters guide says Sound Check determines a track's loudness and uses it to raise or lower the volume so songs play at about the same loudness, and that it can set the volume per album. Apple notes that songs mastered loud end up played at a lower volume, which can make them sound weaker, and that levels which show no overs in the master can still clip once encoded, so it recommends checking the encoded file.

Broadcast: EBU R 128

For television and radio in Europe, EBU R 128 normalizes programmes to -23.0 LUFS and sets a maximum true peak of -1 dBTP in production. It also notes that LUFS is equivalent to LKFS, the unit name ITU-R BS.1770 uses, so a reading in either is the same number.

How this meter measures

The meter follows ITU-R BS.1770, Algorithms to measure audio programme loudness and true-peak audio level: each channel is K-weighted, squared and averaged, and integrated loudness keeps the 400 ms blocks above an absolute gate of -70 LUFS and a relative gate 10 LU below the level of the rest. Loudness range follows EBU Tech 3342, measuring 3 second windows between the 10th and 95th percentiles after gates at -70 LUFS and 20 LU below their average.

Before publishing, it was run against the minimum requirement test signals in EBU Tech 3341 (cases 1 to 6, 9, 10, 12, 13 and 15 to 19) and the loudness range cases 1 to 4 in EBU Tech 3342, and every result fell within EBU's tolerance.

Why two meters can disagree

Integrated loudness should agree within a tenth of a LU between compliant meters on the same file. True peak varies more, because each meter estimates the waveform between samples its own way: EBU R 128 gives a measurement tolerance of plus or minus 0.3 dB for true peak. A different decode, such as an MP3 against its WAV master, also changes the peaks.

Measuring loudness on iPhone

Quint measures integrated loudness and true peak to ITU-R BS.1770 on the iPhone and compares them against the published targets of streaming platforms, alongside a song's key and BPM. It runs on the phone with no account, no sign in and no networking code.

Questions people ask

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