Audio Volume Normalizer (MP3, M4A, WAV and more)
Turn a whole audio file up or down so its loudest sample reaches the level you choose (−6 to 0 dBFS). Works on MP3 and other formats your browser can decode, one file at a time, and saves a WAV file.
Drop your audio file here
MP3, WAV, OGG, M4A, FLAC or AAC (any format your browser can decode)
Max 1 file, up to 50.0 MB each
About the Audio Volume Normalizer
This tool performs peak normalization. It finds the loudest single sample in the whole file, then turns the entire file up or down by one fixed amount so that this peak lands exactly on the target you set, between −6 and 0 dBFS (decibels relative to digital full scale). Because the same gain is applied everywhere, the balance between quiet and loud passages stays exactly as it was; nothing is compressed or limited.
An example: a voice memo whose loudest moment peaks at −12 dBFS, normalized to −1 dBFS, gets +11 dB of gain and plays noticeably louder everywhere. A song that already peaks at −0.2 dBFS gets slightly quieter with a −1 dB target. After processing, the tool shows the peak before, the peak after and the gain applied.
Peak normalization is not loudness normalization. Two tracks with the same peak can sound very different in loudness: one sharp drum hit or a cough can set the peak while the rest of the recording stays quiet. That is why this tool does not measure LUFS and cannot make a playlist sound evenly loud. It is the right tool when a recording is simply too quiet overall, or when you need its peak at a specific level before further editing.
Any format your browser can decode is accepted, including MP3, M4A/AAC, WAV, FLAC and OGG in most browsers. One file is processed at a time, and the result is saved as a 16-bit WAV file rather than MP3. To trim the recording first, use the Audio Cutter.
How to use the Audio Volume Normalizer
- 1
Add an audio file
Drop one file on the drop area or click Browse Files (up to 50 MB). A player lets you listen to the original.
- 2
Choose the target peak
Drag the Target Peak Level slider (−6 to 0 dBFS in 0.5 dB steps) or click a preset: −0.3, −1, −3 or −6 dB.
- 3
Normalize
Press Normalize Audio and wait while the file is decoded, measured and processed. Longer files take a few moments.
- 4
Check and download
Compare Peak Before, Peak After and Gain Applied, listen to the result, then click Download Normalized Audio (WAV).
What it can do
One gain for the whole file
A single gain value for the whole file, so the dynamics of the recording are unchanged.
Turns up or down
Quiet files are raised and files that peak above the target are lowered.
Before and after figures
Shows the original peak, the new peak and the gain applied in dB.
Gain limit for near-silent files
Gain is capped at +20 dB so background hiss in an almost silent file is not blown up; a note appears when the cap is reached.
Uncompressed output
The normalized audio is saved as 16-bit PCM WAV, so no additional MP3 compression is applied.
Limitations
- Peak normalization only; it does not measure or match perceived loudness (LUFS) and does not compress or limit.
- It measures sample peaks. After conversion to MP3 or AAC, peaks between samples can come out slightly higher, so leave −1 dB of headroom if you will compress the file again.
- Output is WAV only, usually much larger than the original MP3.
- One file at a time, up to 50 MB, decoded fully into memory.
Privacy
Your audio is decoded, measured and processed in your browser with the Web Audio API; the file is never uploaded to FlexyPdf's servers.
Frequently asked questions
Is this the same as loudness normalization?
No. Loudness normalization, as used by streaming services, measures how loud a track sounds over time (in LUFS). This tool only looks at the single highest sample, so two normalized files can still sound different in volume.
Which target level should I choose?
−1 dBFS is a common choice that leaves a little headroom for later MP3 or AAC encoding. Use −0.3 dB if the WAV is the final file, and −3 or −6 dB if you will mix it with other sounds.
Will it make my audio distort?
It will not clip. The gain is chosen so that the loudest sample lands on the target, and the target is at most 0 dBFS, so no sample is pushed past full scale.
Why is the output a WAV file and not MP3?
The browser can decode MP3 but has no built-in MP3 encoder, so the result is written as uncompressed WAV. Convert it to MP3 in your audio software if you need a smaller file.
Why did my file only get +20 dB?
The gain is capped at +20 dB. A recording that needs more than that is mostly silence or noise, and boosting it further would mainly amplify hiss.
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