LUFS expresses loudness against digital full scale, while LU expresses a loudness difference from a chosen reference or target. A program measuring -14 LUFS is therefore +9 LU when the target is -23 LUFS, but its audio has not changed.
This distinction matters in meters that let you flip between absolute and relative views. The LUFS and LU target controls in gFractor 1.2.3 beta switch the same loudness information between LUFS and LU, while the target badge sets the zero point for the relative display.
Time still matters after you choose the scale. Momentary, short-term, and integrated LUFS describe different measurement windows, with momentary reacting quickly, short-term smoothing several seconds, and integrated loudness accumulating across the program. Switching a meter from LUFS to LU does not turn integrated loudness into short-term loudness or change how the audio is measured.
LU is useful when you care about relative loudness in music rather than the absolute number. Under EBU R 128 loudness normalization, -23 LUFS is the target reference and therefore 0 LU, so -25 LUFS becomes -2 LU and -21 LUFS becomes +2 LU. A different target moves the relative zero point, which makes LU convenient for seeing how far above or below a working reference you are.
The LUFS vs dB confusion usually comes from treating every decibel-based number as though it answered the same question. The practical split between dBFS and LUFS is level versus program loudness, while LUFS vs RMS adds another distinction because RMS measures signal energy without the same loudness weighting and gating.
This is the most useful way to understand how to use a loudness meter with a movable target. Set the reference for the job, then read LU as distance from that reference instead of mentally subtracting two negative LUFS numbers every time. A relative display is basically doing the comparison math for you.
A LUFS target for mastering should not become a command to keep pushing gain until the meter reaches zero. Loudness and peak safety remain separate, so true-peak headroom can run out before a desired loudness target is reached. LUFS and true peak belong beside each other because one describes program loudness and the other checks reconstructed peak level.
The same caution applies to loudness range. Integrated LUFS can tell you where a complete program lands, while finished-file loudness checks may also need loudness range, true peak, sample peak, and over information. One good-looking loudness number cannot certify the rest of the file.
When measuring LUFS across repeated playback passes, reset the integrated history from the same musical start point. Otherwise, the integrated result can retain audio from an earlier pass and stop describing only the material you meant to compare. Short-term loudness is better for watching local movement while the song plays, while integrated loudness is the whole-program reference. A reset-on-play option makes this discipline automatic instead of relying on a manual reset every time.
For mixing and mastering, the useful target depends on the delivery requirement and the sound you are trying to preserve. There is no single LUFS level you should aim for in every song, and mastering without wrecking the mix still means judging punch, distortion, balance, and dynamics rather than treating loudness as a scoreboard.
Once the distinction is clear, LUFS vs LU becomes simple. LUFS tells you where the measured loudness sits against full scale, while LU tells you how far that same measurement sits from a chosen reference. Change the target and the LU number moves with it, but the underlying audio and absolute LUFS reading stay put.
This distinction matters in meters that let you flip between absolute and relative views. The LUFS and LU target controls in gFractor 1.2.3 beta switch the same loudness information between LUFS and LU, while the target badge sets the zero point for the relative display.
LUFS is absolute, and LU is relative
If you are sorting out what LUFS means in music production, start with the reference. LUFS means loudness units relative to full scale, and the measurement uses frequency weighting plus time-based loudness calculation rather than simply watching the highest sample. The basic idea behind how LUFS work is closer to program loudness than peak level.Time still matters after you choose the scale. Momentary, short-term, and integrated LUFS describe different measurement windows, with momentary reacting quickly, short-term smoothing several seconds, and integrated loudness accumulating across the program. Switching a meter from LUFS to LU does not turn integrated loudness into short-term loudness or change how the audio is measured.
LU is useful when you care about relative loudness in music rather than the absolute number. Under EBU R 128 loudness normalization, -23 LUFS is the target reference and therefore 0 LU, so -25 LUFS becomes -2 LU and -21 LUFS becomes +2 LU. A different target moves the relative zero point, which makes LU convenient for seeing how far above or below a working reference you are.
The LUFS vs dB confusion usually comes from treating every decibel-based number as though it answered the same question. The practical split between dBFS and LUFS is level versus program loudness, while LUFS vs RMS adds another distinction because RMS measures signal energy without the same loudness weighting and gating.
The target changes the scale, not the audio
Suppose a mix sits at -12 LUFS integrated. With a -14 LUFS target, the relative display reads +2 LU, while moving the target to -10 LUFS makes the same unchanged mix read -2 LU. The absolute LUFS measurement stays at -12 because the target setting only changes the reference used for the LU display.This is the most useful way to understand how to use a loudness meter with a movable target. Set the reference for the job, then read LU as distance from that reference instead of mentally subtracting two negative LUFS numbers every time. A relative display is basically doing the comparison math for you.
A LUFS target for mastering should not become a command to keep pushing gain until the meter reaches zero. Loudness and peak safety remain separate, so true-peak headroom can run out before a desired loudness target is reached. LUFS and true peak belong beside each other because one describes program loudness and the other checks reconstructed peak level.
The same caution applies to loudness range. Integrated LUFS can tell you where a complete program lands, while finished-file loudness checks may also need loudness range, true peak, sample peak, and over information. One good-looking loudness number cannot certify the rest of the file.
When measuring LUFS across repeated playback passes, reset the integrated history from the same musical start point. Otherwise, the integrated result can retain audio from an earlier pass and stop describing only the material you meant to compare. Short-term loudness is better for watching local movement while the song plays, while integrated loudness is the whole-program reference. A reset-on-play option makes this discipline automatic instead of relying on a manual reset every time.
Use the reading that answers the job
Absolute LUFS is usually clearer when you need to record, compare, or communicate an actual measured loudness value. Relative LU becomes faster when you already have a defined target and mainly need to know the offset, especially during repeated passes where +1 LU and -0.5 LU are easier to scan than constantly comparing absolute numbers.For mixing and mastering, the useful target depends on the delivery requirement and the sound you are trying to preserve. There is no single LUFS level you should aim for in every song, and mastering without wrecking the mix still means judging punch, distortion, balance, and dynamics rather than treating loudness as a scoreboard.
Once the distinction is clear, LUFS vs LU becomes simple. LUFS tells you where the measured loudness sits against full scale, while LU tells you how far that same measurement sits from a chosen reference. Change the target and the LU number moves with it, but the underlying audio and absolute LUFS reading stay put.
