Use the free Audio Volume Booster below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
Why some recordings are too quiet
Quiet recordings are everywhere. A phone held too far from a speaker. A lecture recorded from the back of a hall. A voice memo made in a noisy street where the speaker kept their voice down. An old cassette transfer done cautiously to avoid distortion. The content is fine, but the level is so low that listeners must turn their volume to maximum and still strain, and every bit of background hiss gets amplified along with the voice when they do.
This volume booster fixes the level problem in your browser. Upload the quiet file, choose a boost, and download a louder WAV file. A gain stage raises the level, and an optional limiter stage keeps the loudest peaks from clipping into harsh distortion. Nothing is uploaded, and the original file is never altered.
How gain and limiting work
Gain is simple multiplication. A gain of 2x doubles every sample value, which raises the level by about 6 decibels. A gain of 3x raises it by about 9.5 decibels, and 4x by about 12 decibels. The problem is the ceiling. Digital audio has a hard maximum: samples cannot exceed full scale. If a peak was already at 0.6 and you apply 2x gain, it tries to reach 1.2, which is impossible, so it gets chopped flat at 1.0. That chopping is clipping, and it sounds harsh, especially on voices and drums.
The limiter solves this with a compressor that watches the level and turns down only the loudest moments. The threshold is set at minus 6 decibels, with a fast attack and a gentle release, so peaks are caught quickly and the level recovers smoothly. The result is louder overall without flat-topped peaks. It is not magic: a limiter cannot restore detail that was already lost, and heavy limiting can make audio sound squashed. But for a quiet recording with occasional peaks, it is the right tool.
How to use it
Upload your file and look at the process step. Start with 2x gain and the limiter switched on, which is the default. Press Process and read the reported peaks before and after. If the peak after is close to 1.0 and the audio still sounds quiet, the recording may need more than gain: it may have a noise problem, or the quiet parts may be much quieter than the peaks, in which case a compressor-heavy workflow in a proper editor will serve you better than a single gain stage.
If the limiter is switched off and the peak before multiplied by the gain exceeds 1.0, the tool warns you that clipping will happen. Heed that warning. Either turn the limiter back on, or choose a smaller gain. There is no benefit to a louder file that crackles on every loud syllable. Listeners forgive a slightly quiet file; they do not forgive distortion.
When boosting is not the answer
Boosting raises noise exactly as much as it raises signal. A whisper recorded in a noisy room will still have room noise after boosting, only louder. If the noise is the problem rather than the level, you need noise reduction, not gain. Similarly, a recording that is quiet because the microphone was faulty, with dropouts or hum, will not be fixed by volume alone. Gain is for level problems, not for damage problems, and recognising the difference saves a lot of wasted effort.
For straightforward quiet recordings, though, this tool is all you need. Two minutes, one slider, one download, and a file that plays at a comfortable level on any device, without an account and without sending your audio to anyone.