1Upload the MP3 audio files you want brought to a consistent loudness.
2There is nothing to set: the loudness is brought to -16 LUFS (EBU R128), with true peaks kept below -1.5 dBTP.
3Run the analysis; integrated loudness and true peak are measured before any gain is decided on.
4Download the normalized MP3 file.
Normalize MP3 Loudness FAQ
Does the source format affect normalisation?
+
It does. MP3 is the universal lossy codec — nothing refuses to play it, at the cost of poorer quality per bit than AAC or Opus. That determines whether the corrected audio can be written back exactly or has to be re-encoded.
Anything specific to MP3 here?
+
Yes — MP3 frames are fixed-size blocks, so a cut lands on a frame boundary and gapless playback markers do not survive a re-encode. Worth knowing when the goal is a consistent set rather than one file.
How does Normalize MP3 Loudness decide the right level?
+
Concretely, loudness is measured against the EBU R128 standard and a single gain adjustment brings the whole file to the target LUFS — which is what streaming platforms actually measure, and is not the same thing as peak normalisation. The file is measured first and the correction follows from the measurement, rather than a fixed gain being applied and hoped for.
What is the difference between this and just turning it up?
+
A volume change applies a number you chose. Normalisation measures how loud the file actually is and computes the gain needed to hit a target, so ten files recorded at ten different levels all arrive at the same one.
What can I upload to Normalize MP3 Loudness?
+
MP3, AAC, M4A, OGG, Opus and WMA are the lossy codecs handled directly, and lossless sources (WAV, FLAC, AIFF) can go in the same batch. The codec is probed from the stream, so an incorrectly named file still works.
Is there a file size limit on Normalize MP3 Loudness?
+
Yes: free accounts process audio up to 15 MB per file, which at typical bitrates is several hours of material; ffmpeg does the decoding and encoding, exactly as it would on a desktop. That is the most generous cap on the site after video, and audio work rarely runs into it.
Why would a modern-format site run Normalize MP3 Loudness?
+
WEBP.to is built around the modern replacement for both of the old defaults: one format that does lossy, lossless, alpha and animation, and reliably lands smaller than the JPEG or PNG it came from. People arrive here having decided the old defaults are costing them bandwidth, and that decision immediately raises the rest: what size, what quality, what happens to the transparency. Normalize MP3 Loudness is on the same upload and the same account so those questions get answered in one place.
Once Normalize MP3 Loudness has run, what is worth doing next?
+
The converter on this site moves images to and from WebP, PNG, JPG and AVIF, which is where you decide whether a smaller file is worth losing the older browsers. Doing it in that order matters: pick the pixels first and the container afterwards, because the container is the cheap decision and the pixels are the expensive one.
Do the sibling sites run something different?
+
The engines are identical — same libraries, same workers, same caps. What is different is the opinion attached, and the opinion here rests on a property of the format this site is named after: the same .webp extension can hold a lossy VP8 frame, a lossless one, or an animation, so the sensible processing path is decided per file rather than per extension.
What happens to my file, and is an account required?
+
No account is needed. Uploads and results are kept for about 24 hours, which leaves time to download the result, and are then deleted automatically; nobody reads, lists or indexes them. Several files in one job need a paid plan.
