What normalizing means
To normalize audio is to change its level so that it meets a target. You do not choose the gain yourself; the tool measures the file and calculates how much to raise or lower it. This makes recordings from different sources consistent, and it brings quiet files up to a useful level without guessing. The measurement and processing happen in your browser, without uploading the file.
Peak or loudness?
- Peak normalization finds the single loudest sample and sets it to the target, for example -1 dBFS. The rest of the file is moved by the same amount. It guarantees that nothing clips, but it does not make files sound equally loud: a recording with one loud clap and quiet speech stays quiet.
- Loudness normalization measures the average loudness as the ear hears it, in LUFS (Loudness Units relative to Full Scale), the unit defined by the international standard ITU-R BS.1770. Two files at -16 LUFS sound about equally loud, even if their peaks are different.
Common loudness targets
| Use | Target |
|---|---|
| Podcasts, audiobooks, voice | -16 to -19 LUFS |
| Music streaming | -14 LUFS |
| YouTube and online video | -14 LUFS |
| Broadcast TV (Europe) | -23 LUFS |
| Peak-safe master for any use | -1 dBFS peak |
Streaming services turn loud tracks down to their target anyway, so making a file louder than about -14 LUFS rarely helps and can reduce quality.
An example
Imagine three podcast episodes recorded on different days. The first peaks at -2 dBFS and measures -20 LUFS, the second peaks at -9 dBFS and measures -24 LUFS, the third peaks at -1 dBFS and measures -15 LUFS. With peak normalization to -1 dBFS, the second episode gets +8 dB, but the first and third barely change, so they still sound different. With loudness normalization to -16 LUFS, the first gets +4 dB, the second +8 dB and the third -1 dB, and all three now sound equally loud. That is why loudness normalization is the better choice for a series of files, and peak normalization is mainly a safety step for single files.
Tips
- Leave a little headroom. A peak target of -1 dBFS instead of 0 prevents small overs after MP3 or AAC encoding.
- Clean before you normalize. Normalization raises noise too. Use Noise Reduction first on noisy recordings.
- Normalize last. Effects like EQ, reverb or bass boost change the level, so normalize at the end of your work.
- For many files, such as podcast episodes or a playlist, use the same loudness target for each one. When joining files, Merge Audio can match loudness automatically.
If you prefer to choose the exact gain yourself, use Amplify. Normalizing does not change the tone of a file: it moves the whole recording up or down by the same amount.