Audio Volume Booster & Normalizer
Load a quiet recording and make it louder: boost by decibels, normalize the peak to a target level or match loudness with RMS normalization. A look-ahead limiter keeps peaks from clipping, and you can compare before and after before you download.
Scales the whole file so its loudest sample reaches the target. −1 dBFS leaves a little headroom for MP3 encoding.
Matches average loudness between files. Keep the limiter on so peaks cannot clip.
How to use the Audio Volume Booster & Normalizer
- Choose an audio file or drop it onto the box. It is decoded locally in your browser.
- Pick a mode: Boost by dB for a fixed gain, Peak normalize to bring the loudest point to a target, or Loudness (RMS) to match average volume.
- Keep the limiter on when boosting a lot. It turns down only the short peaks that would otherwise clip.
- Check the result: look at the statistics and the After waveform (red means clipping) and press Play preview to compare Before and After.
- Download the louder file as WAV or MP3.
Decibels and volume percentage
Digital gain multiplies every sample by a factor. In decibels the factor is gain(dB) = 20 × log₁₀(factor), so factor = 10dB/20.
| Gain | Amplitude factor | Shown as | Typical effect |
|---|---|---|---|
| −6 dB | ×0.50 | 50% | Half the amplitude |
| +3 dB | ×1.41 | 141% | Slightly louder; double the power |
| +6 dB | ×2.00 | 200% | Clearly louder |
| +10 dB | ×3.16 | 316% | Sounds about twice as loud |
| +20 dB | ×10.0 | 1000% | Very quiet recordings, e.g. distant voice |
| +30 dB | ×31.6 | 3162% | Extreme; noise is boosted too |
Common loudness targets
Broadcasters and streaming services measure loudness in LUFS (EBU R128 / ITU-R BS.1770), which weights frequencies the way we hear them. This tool uses plain RMS level in dBFS, which is simpler but behaves similarly for most speech and music: a louder RMS target means a louder file.
| Use | Peak target | Typical RMS level |
|---|---|---|
| Podcast / voice recordings | −1 dBFS | about −20 to −16 dBFS |
| Music for streaming | −1 dBFS | about −14 to −10 dBFS |
| Audiobooks (ACX requirement) | −3 dBFS max | −23 to −18 dB RMS |
| Sound effects / samples | −0.3 to −1 dBFS | depends on the sound |
Tips for boosting quiet audio
- Start with peak normalization. It is the "free" gain: the file gets as loud as it can without any limiting.
- Use the limiter for more loudness. Short peaks such as plosives, claps or drum hits usually set the peak level; limiting them by a few dB makes the whole file louder with little audible change.
- Watch the noise. Boosting raises background hiss and hum by the same amount as the voice or music. Very high gains on noisy recordings may need noise reduction first.
- Leave headroom for MP3. MP3 and AAC encoding can create small overshoots, so a ceiling of −1 dBFS is safer than −0.1 dBFS for lossy formats.
- Export WAV for further editing and convert to MP3 only at the end to avoid repeated lossy encoding.
Why clipping sounds bad
A digital file cannot store values above 0 dBFS. If gain pushes a waveform past that limit, the tops of the waves are cut flat ("hard clipping"). The flattened parts add harsh, buzzing harmonics that were not in the original sound, and once they are in a file they cannot be removed. The After waveform marks every clipped section in red and the statistics count the clipped samples, so you can lower the gain or switch the limiter on before you download.
Frequently asked questions
How much louder is +6 dB?
+6 dB doubles the amplitude of the signal (about 200%), and +20 dB multiplies it by 10. Perceived loudness roughly doubles every +10 dB. The percentage next to the gain shows the amplitude factor.
What is the difference between peak and loudness normalization?
Peak normalization scales the file so the single loudest sample hits the target, for example −1 dBFS. It never clips but a file with one loud click may hardly get louder. Loudness (RMS) normalization scales by the average level, so files sound similarly loud; it can push peaks over 0 dBFS, which the limiter then catches.
What does the limiter do?
When the boosted signal would go above the ceiling, the limiter smoothly reduces the gain just before and during that peak, then releases it again. Because it looks a few milliseconds ahead, no sample exceeds the ceiling and you avoid the harsh distortion of digital clipping.
What is dBFS?
Decibels relative to full scale. 0 dBFS is the loudest level a digital file can store; everything quieter is negative. −1 dBFS is about 89% of full scale.
Why does my MP3 still sound distorted after boosting?
If the limiter is off or the gain is extreme, peaks are clipped and sound harsh; the clipping counter and red parts of the waveform show this. Turn the limiter on, lower the gain or use a ceiling of −1 dBFS, which also leaves room for MP3 encoding, which can add small overshoots.
Can I make a video's audio louder?
Many browsers can decode the audio track of MP4 or WebM files, so you can load them here and export the boosted audio as WAV or MP3. The video itself is not changed.
Are my files uploaded?
No. Decoding, processing and encoding all happen in your browser on your device.