Free online LUFS checker

Upload a track and get its integrated LUFS (ITU-R BS.1770-4), short-term loudness, loudness range (EBU R128), and 4× oversampled true peak — measured the same way streaming platforms measure it. Then see exactly how far you are from your genre's loudness target and what to change.

What LUFS actually measures

LUFS stands for Loudness Units relative to Full Scale. It is the unit defined by ITU-R BS.1770-4 for programme loudness, and it exists because peak level and perceived loudness are different things. A track with a very high peak can sound quiet if the energy between the peaks is low, and a dense, compressed track can sound much louder at the same peak level. LUFS tries to put a single number on how loud a piece of audio is likely to feel to a listener.

One loudness unit (LU) equals one decibel, so a change of 3 LU is a change of 3 dB in level. The difference is the reference: LUFS values are always negative for normal music because 0 LUFS would correspond to a full-scale signal in the measurement's own weighting. A modern loud master might read around -8 to -10 LUFS; a dynamic acoustic recording might read -18 or lower.

The reason it matters in practice is that almost every streaming service now measures loudness and adjusts playback level to a reference. If you know how the number is built, you can predict what a platform will do to your master before you upload it.

How the measurement works: K-weighting and gating

BS.1770-4 builds the measurement in a fixed sequence. First the signal passes through K-weighting, a two-stage filter. The first stage is a high-frequency shelf of roughly +4 dB starting around 1.5 kHz, which models the acoustic effect of the head. The second is a high-pass filter near 38 Hz that discounts very low frequencies the ear is insensitive to. The result is that a loud sub-bass note counts for less than a mid-range sound of the same level, and presence-region energy counts for slightly more.

Next, the filtered signal is squared and averaged in blocks of 400 ms, overlapping by 75 percent. For stereo, left and right are each weighted equally and their power is summed, then converted to a logarithmic value. That block value is the basis of everything else.

Integrated loudness then applies gating. Blocks below an absolute gate of -70 LUFS are discarded so digital silence does not drag the average down. Then a relative gate removes blocks more than 10 LU below the average of the remaining blocks, so long quiet passages do not dilute the figure. The mean of what survives is the integrated loudness. Gating is why a song with a very quiet intro does not read artificially soft.

Momentary, short-term and integrated: three windows

The same K-weighted power is reported over three different windows, and each answers a different question.

Momentary loudness uses a 400 ms window. It moves quickly and shows how loud the current beat or phrase is. It is useful for finding which hit or chorus entry jumps out.
Short-term loudness uses a 3 second window. It tracks sections and is the best view for judging whether a chorus is genuinely louder than a verse, and by how much.
Integrated loudness covers the whole programme with gating applied. It is the single number platforms use for normalization, so it is the one you compare against targets.

How streaming normalization uses the number

Loudness normalization means the service measures each track, compares it to a reference level, and applies a gain so that tracks play back at similar loudness. The reference is the platform's choice. Commonly cited reference levels are about -14 LUFS for Spotify and YouTube, about -16 LUFS for Apple Music (Sound Check), and -23 LUFS for broadcast under EBU R128. Treat these as approximate: platforms change their behaviour, and some apply normalization only by default settings the listener can switch off.

The two cases differ. If your master is louder than the reference, the service turns it down. A master at -9 LUFS on a -14 LUFS platform is reduced by about 5 dB. If your master is quieter, behaviour varies: some services only attenuate, others also raise quiet tracks, sometimes with a limiter. Do not assume a quiet master will be rescued.

The consequence is the key insight: after normalization, a heavily limited master does not play louder than a dynamic one. It plays at the same loudness but with its transients flattened. Chasing a very high LUFS figure for a streaming release buys nothing except lost dynamics. Radio, club play, and listeners with normalization off are the situations where raw level still counts.

Reference ranges for common destinations

These are reference ranges, not rules. Check each platform's current published guidance before delivery.

EBU R128 broadcast: -23 LUFS integrated, with true peak at or below -1 dBTP.
Spotify and YouTube: normalization reference about -14 LUFS integrated.
Apple Music: about -16 LUFS integrated.
Loud pop, hip-hop and electronic masters: commonly land between -14 and -8 LUFS integrated before normalization.
Jazz, classical, acoustic and folk: commonly -20 to -14 LUFS, and often better left quiet.
Pre-master mixes: no loudness target applies. Leave generous headroom, with peaks well below 0 dBFS, for the mastering stage.

How to hit a target without crushing the mix

Loudness comes from the average level, but the ceiling is the peak level, so the gap between them (see peak-to-loudness ratio) is the budget you are spending. To raise loudness without damage, reduce the peaks that stick out rather than squashing everything.

Measure the current integrated LUFS and true peak of the full song, not a loop.
Work out the gap to your target. If the master reads -12 LUFS and you want -10, you need 2 dB more loudness.
Start upstream. Tame the few loudest transients with clipping or a fast compressor on the drum bus, so the limiter has less peak to remove.
Set the limiter ceiling to about -1 dBTP and increase input gain until integrated loudness reaches the target. Aim for no more than 2 to 4 dB of gain reduction on average.
Listen at matched loudness. Turn the unlimited version down by the same amount, so you judge quality instead of volume.
If the chorus sounds smaller than before, back off by 0.5 to 1 LU. The target is a guide, not a contract.

Worked example

A pop master measures -9.5 LUFS integrated and -0.4 dBTP. Uploaded to a -14 LUFS platform, the service applies about -4.5 dB of gain. The true peak becomes -4.9 dBTP and the listener hears the song at -14 LUFS, but with the squashed dynamics of a -9.5 master.

Now consider a version limited to -12.5 LUFS with a -1.0 dBTP ceiling. It is turned down only 1.5 dB on that platform, ends at -14 LUFS with a peak of -2.5 dBTP, and has about 2.4 dB more peak-to-loudness ratio (11.5 versus 9.1) than the first version. At the same playback loudness it will usually sound punchier, because the drums were not flattened to get there.

Both versions reach the listener at the same level. The only difference is how much of the original dynamics survived, and the numbers let you see that before you commit.

Common mistakes and a measurement checklist

Checklist before delivery: measure the final bounce, not the session; read integrated LUFS over the whole file; check loudness range and true peak alongside it; compare against the destination's reference; re-measure after any change to the chain.

Measuring a section or a loop and reporting the result as the track's loudness. Integrated loudness needs the full programme.
Comparing numbers from meters that disagree because one is not K-weighted, or reports RMS dBFS instead. Confirm the meter is BS.1770 compliant.
Using short-term or momentary maximum as the headline value. Normalization uses integrated loudness.
Judging a quieter master as worse without matching playback loudness. Louder almost always sounds better in a quick A/B.
Ignoring true peak while pushing loudness. A master can pass LUFS and still clip after encoding.
Normalizing a pre-master mix to a streaming target, which removes headroom the mastering engineer needs.

What you get

Integrated LUFS, LRA, and true peak (dBTP) via broadcast-standard metering.
Compared against streaming targets — Spotify/YouTube −14, Apple −16 — and your genre.
Tells you not just the number but whether it's a problem and how to fix it.
Free with a quick sign-up, no install — runs in your browser.

Questions

What LUFS should I master to?

For most streaming, −14 to −10 LUFS integrated is the modern competitive range. Genre matters — Unveil scores you against your genre's actual target rather than one global number.

How is true peak measured?

4× polyphase oversampling per ITU-R BS.1770-4 Annex 2, so inter-sample peaks that clip after lossy encoding are caught.

Analyze your mix — free