Use the free tool below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
What LUFS actually measures
LUFS stands for Loudness Units relative to Full Scale. It measures how loud a listener perceives a piece of audio to be, over time, rather than how high its loudest peak reaches. Two songs can share the same peak level and still feel very different in loudness: a heavily compressed song stays near its peak almost all the time, while a dynamic song touches its peak only on drum hits and sits much quieter the rest of the time. LUFS captures that difference by averaging energy over the whole song, with a frequency weighting that matches human hearing and with quiet passages gated out, so silence does not drag the average down. The international method is ITU-R BS.1770, and a true measurement needs the full audio file, not a handful of numbers.
That honesty matters for this tool. This calculator does not measure your audio. It takes momentary LUFS readings you have already taken from your own meter, at several points in the song, and combines them into an integrated estimate using the energy-mean formula: ten times the logarithm of the average of ten to the power of each reading divided by ten. Loud sections count more than quiet ones, because energy averaging works in power, not in simple arithmetic. If your readings are -14, -13.5, -15 and -14, the estimate lands near -14, not at the plain average of the numbers, because the louder readings carry more energy. Treat the result as a planning estimate, and always confirm a final master with a real loudness meter over the full file.
How to use the calculator
- Play your song through a loudness meter and note several momentary LUFS readings from loud and quiet sections.
- Type those readings into the tool, separated by commas.
- Choose a target to compare with, for example -14 LUFS, a common streaming target.
- Optionally enter your peak and RMS levels to see the crest factor, which is peak minus RMS.
- Read the integrated estimate, the range of your readings, and how far you sit from the target.
A worked example
Suppose your readings are -16 in the verse, -13 in the chorus, -15 in the bridge and -12 in the final chorus. A plain average would give -14, but the energy mean gives about -13.6, because the loud choruses dominate the energy. Against a -14 target, you sit about 0.4 loudness units above target, which is close: most streaming services normalise within a small range, and a difference under one unit is rarely worth chasing with more compression. If instead your readings were all around -20, you would sit six units below target, and the platform would turn your song up, which also turns up its noise floor. The fix is not always louder mastering; often it is a better balance, so quiet sections do not vanish when the whole song is turned up.
Crest factor and dynamics
The crest factor, peak minus RMS, tells you how much dynamic range your music keeps. A crest factor of six decibels means a very compressed, constantly loud sound. A crest factor of fourteen decibels means punchy drums over a quieter body, which many listeners prefer even if the LUFS number is lower. Loudness targets pushed many masters toward small crest factors in the past, but streaming normalisation has reduced that pressure: once a platform turns every song to the same loudness, the over-compressed song gains nothing and loses its punch. Aim for a crest factor that suits the music, check the integrated estimate against your target, and leave at least one decibel of true-peak headroom so the encoding to a streaming format does not clip.
Targets are guides, not laws
Published streaming targets change, and different services publish different numbers, so treat any target in this tool as a common reference, not as a rule your music must obey. Check the current specification of the service you distribute to, and remember that a song slightly above or below target is not rejected: it is simply turned up or down to match. What damages a song is not missing a target by a unit or two, but crushing its dynamics to hit a number, or leaving so little headroom that encoding clips the peaks. Use this estimator to plan, use a real meter to confirm, listen at matched loudness, and let the music, not the number, make the final decision.
Related calculators
- Spanish version
- Reel-to-Reel Tape Calculator – Playing Time from Length and Speed
- Decibel Ratio Calculator – dB Gain to Amplitude and Power Ratios