1Upload the AAC 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 AAC file.
Normalize AAC Loudness FAQ
What is the difference between this and just turning it up?
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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.
Does the source format affect normalisation?
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It does. AAC is the MP4-family lossy codec, audibly better than MP3 at the same bitrate and the default for Apple devices. That determines whether the corrected audio can be written back exactly or has to be re-encoded.
Does Normalize AAC Loudness cost anything?
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No. Normalize AAC Loudness is free without an account, and nothing is added to the audio. The upload and the result are deleted automatically about 24 hours after the job, which leaves time to download the result.
What can I upload to Normalize AAC Loudness?
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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.
Why does a PDF site host Normalize AAC Loudness?
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PDF.to exists because PDF is where documents go to be shared and the worst place to keep them while they are still being worked on, so nearly every job here is about getting something into or out of that state deliberately. A document rarely arrives in the state it needs to leave in: it is too big, in the wrong order, locked, or a scan with no text in it. Normalize AAC Loudness sits on the same upload and the same account as the conversions because those jobs turn up together.
What should I do with the result once Normalize AAC Loudness is finished?
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The converter on this site moves documents between PDF, Word, images, plain text and eBook formats in either direction, so whatever comes out of a tool here has somewhere to go next without a second upload. Running that after Normalize AAC Loudness rather than before keeps the document structure intact through the step that is most likely to flatten it.
Is Normalize AAC Loudness here the same tool the sibling sites run?
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The engines are shared — the same document toolchain, the same workers, the same limits. What a PDF site adds is a view on when a file should stay a document and when it genuinely wants to become something else, which is the decision most tools quietly make for you. It also starts from one fact about the format this site is named after: a PDF is an object graph, not a page image, so text stays selectable and vectors stay sharp no matter what happens to the raster content inside it.
Do I need an account, and does anything get kept?
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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.
