LUFS stands for Loudness Units relative to Full Scale. It is the standard way platforms and broadcasters describe how loud a whole track feels, not just how high the loudest sample is. Spotify, YouTube, Apple Podcasts and many broadcasters aim for a target integrated LUFS value so playlists do not jump in volume from song to song.
A peak meter only watches the tallest sample. LUFS models human hearing: it weights frequencies, averages over time, and can ignore very quiet passages (gating). Two tracks can share the same peak and still sound very different in loudness — the one with denser average energy will read higher in LUFS.
Platforms may turn a louder upload down toward their target. They rarely turn a quiet upload up, so a file far below target stays soft relative to everything else in the feed.
Integrated LUFS is the loudness of the whole file (or a long segment). Short-term and momentary values describe shorter windows and help you see whether a chorus or a shout spikes much louder than the rest. For delivery specs, integrated LUFS plus a true-peak limit is what most checklists ask for.
A voice memo peaks at −1 dBFS but measures around −28 LUFS: it looks “almost full scale” on a peak meter, yet it will sound quiet next to a podcast mastered to −16 LUFS. Raising gain (or normalizing carefully) moves integrated LUFS up without necessarily maxing the peak first.
Sound Booster’s Audio Quality Check runs in the browser, reports integrated LUFS and related levels, and suggests how many dB you would need to move toward common targets. For a gentle level lift after you know the numbers, use the Volume Booster normalize flow.
LUFS does not treat every frequency equally. A weighting filter reduces the influence of very low bass and boosts the upper midrange where ears are most sensitive, so a thumping sub-bass note does not count as much as the same energy in the voice range. A gate then ignores passages that are very quiet, so long silences do not drag the final number down. The standard behind this, used in broadcast and streaming, applies an absolute gate far below normal listening level and a relative gate that skips sections much quieter than the programme average.
LUFS is an absolute reading on a scale where 0 means full scale, so almost every real file measures a negative number. LU, loudness units, is a relative step: one LU is the same size as one decibel. If a track measures −20 LUFS and the target is −16 LUFS, you are 4 LU too quiet, and about 4 dB of gain moves it to the target. That is why meters often show differences in LU and positions in LUFS.
Two files can have the same integrated LUFS but feel very different. A heavily compressed pop track stays near one level all the way through. A film mix or a conversational podcast has quiet passages and loud ones. Loudness range, often shown as LRA, describes that spread. A wide range is not a fault, but a podcast with a very wide range forces listeners in cars and on trains to keep adjusting the volume.
See integrated LUFS, peaks and recommendations on a local file — no upload.
Open Quality CheckBoost or normalize after you know how far the file sits from your target.
Open Volume BoosterWhen everything is limited to the digital ceiling, peak meters all look the same and playlists still feel uneven. LUFS-based normalization is the industry answer: services turn hot masters down toward a shared target so a carefully dynamic mix is not punished for having headroom. That is why chasing only 0 dBFS peaks is a poor goal for Spotify or YouTube uploads.
If your track measures far above the platform target, listeners may hear an automatic turn-down. If it sits far below, it stays soft until they reach for the volume knob. Measuring integrated LUFS before you upload is the practical way to avoid both surprises.
For a useful note in your project: integrated LUFS, true-peak maximum, and whether the file is music, speech, or a mix of both. Speech-heavy shows often sit a little lower than dense music and still sound clear. Re-check after any normalize or limiter pass — one export can shift the number by several LU.
No. Louder is not the same as better. If you exceed a platform’s target, it may turn your file down, and heavy limiting to reach a high number can make music sound flat. Aim for the delivery target and keep dynamics healthy.
Small differences come from the measurement window, how the file was decoded, whether true-peak oversampling was applied and how very short files are treated. A difference of a few tenths is normal; a large gap usually means a different measurement type was used.
For listening on a phone, many people aim near the −16 LUFS region used for spoken content. A memo that measures far lower, such as −28 LUFS, needs a clean level increase, not just a peak-based boost.
In normal use it will not. The scale is relative to full scale, and real programme material sits below it. A reading near zero would mean extreme, almost constant clipping.
