Boosting a video by guesswork means trying a number, listening, and trying again. An audio normalizer skips the guessing. It measures the loudest point of your sound and lifts the whole track until that point sits just below the maximum.
Drop a video, check the numbers in the panel, and press Change volume. The work runs in your browser, so the video is never uploaded. Below you will find exactly what normalising does, what it does not do, and when to pick a different mode.
How to normalize video audio
- Drop your video onto the page. You can add more than one.
- The mode is already set to Normalise. There is no slider to move.
- Read the panel. 'Loudest point now' is where the sound peaks today, 'After' is where it will peak, and 'Change' is the difference in dB.
- Press Change volume and save the new MP4. The file name ends in _normalised.
The three numbers are shown in decibels (dB), a scale for loudness. A change of +6 dB roughly doubles the strength of the signal, and -6 dB halves it. You do not need to understand the scale to use the tool. Just compare 'now' with 'After' and decide whether that is what you want.
While the tool reads the sound, the panel says 'Reading the sound...' for a moment. Once the numbers appear, you know exactly what will happen before anything is saved.
Your original video is not changed. If you prefer to choose the amount yourself, switch to Adjust on the main Change video volume page.
What an audio normalizer does to the sound
An audio normalizer finds the single loudest sample in your video's sound and applies one fixed gain to the whole track, so that sample lands at -1 dBFS. Every digital recording has a ceiling, called full scale, measured as 0 dBFS, so -1 dBFS leaves a small safety gap below it. Because everything is set from that one peak, this is called peak normalization.
| Case | Loudest point now | What happens |
|---|---|---|
| A quiet recording | Well below -1 dBFS | The whole sound is lifted. The panel shows a positive change. |
| A recording already near the top | Close to -1 dBFS | Little or no change. |
| A recording above -1 dBFS | Higher than -1 dBFS | The sound is brought down a little to reach -1 dBFS. |
| A very quiet recording | Below about -21 dBFS | The lift stops at +20 dB, so it ends below -1 dBFS. |
Because the same gain is applied to everything, the shape of the sound does not change. Loud and quiet parts keep the same balance. Everything simply moves up or down together.
The 20 dB limit
The lift is capped at 20 dB so that a near-silent file is not blown up into noise. When the cap applies, a note says so: the video is very quiet, the change stops at +20 dB, and the loudest point ends below -1 dBFS.
Peak is not the same as perceived loudness
Normalising works from the peak. It does not measure how loud a clip feels over time. Two clips with the same loudest point can still sound different in loudness. For matching by ear, you can use Adjust and listen.
When to normalise instead of boosting
Both choices make a quiet video louder. They suit different situations.
- Use Normalise when you do not know how much to add. A quiet video gets more, and a loud one gets little or none.
- Use Normalise for a batch from different sources. Each file is measured and set on its own, so you do not need a different number for each.
- Use Normalise when you must avoid clipping. The loudest point is placed below the maximum, so it cannot be cut flat by this gain.
- Use boost video volume when you want a specific amount, such as exactly double, and are happy to watch the waveform for red.
If the result is too loud for your taste, lower it with make a video quieter. The tools work together: you can normalise first, then turn the result down to suit.
Normalising a batch
Drop in as many clips as you like. The numbers in the panel describe the first file. Each file is measured and set on its own when the job runs. You can then save them one by one or as a zip.
Videos that suit normalising
Normalising is a good first step for almost any video that sounds too quiet, and it earns its keep in a few situations in particular.
- A folder of clips from one event, filmed on different phones, each with its own level.
- A recording made with the microphone gain set too low.
- A screen capture or lecture that you want ready for upload without hand-tuning each file.
- A clip that you will place in a longer video and want to peak at a known level.
- An old transfer that comes out faint, where you cannot tell how much to add.
- A recording you will export as a WAV for editing. Normalise it first, and the sound reaches your editor with a known peak.
It is less useful when the problem is not the level. Normalising cannot remove noise, fix a muffled voice or balance a loud background against soft speech. It moves the whole sound up or down together, and nothing else.
Check the result by ear
The numbers tell you the peak, not how the clip feels. After you save, play the new video where it will be heard. If it is louder than you want, run the original again in Adjust at a lower level, or turn the result down with Make a video quieter.
Have an MP3 or WAV rather than a video?
This page takes video files only, such as MP4, MOV, MKV or WebM. If you drop an MP3 or a WAV, it is not loaded, and the page says it is not a video file. When the sound comes from a video, normalise the video here first, then save its sound with MP4 to WAV or MP4 to MP3.
Private, free and ready in your browser
The measuring and the change both happen on your own computer, in current Chrome, Edge or Firefox. The video is not uploaded, and the server does no video work. There is no account, no watermark and no charge. Video tools do not count towards the daily limit for document conversions.
If your browser cannot read the sound ahead of time, the panel says so, and the loudest point is measured while the job runs instead. Most videos have no size limit, and some files, such as certain AVI or WMV videos, take longer and can be up to 2 GB.
Let the tool set the level for you
To normalize video audio, drop your file in the tool above, read the three numbers in the panel, and press Change volume. It is quick to check, free to use, and your video stays on your computer.
Whenever a clip sounds too quiet, let the audio normalizer set the level first and adjust by hand only if you need to. If you only need to remove the sound, mute the video instead.
