Volume Booster
Make a quiet recording louder and normalise inconsistent levels
100% In-Browser · Private & Instant · Free Forever
Your file is decoded, processed, and re-encoded in this browser tab. Nothing is uploaded to an OfflineTTS processing API.
Interactive Workspace
Volume Booster
Raise a quiet recording to a usable level, or bring several files to a consistent loudness before you edit them together. The tool measures the file first — peak, average RMS, and crest factor — so you can see how much headroom actually exists before applying gain.
Why measure before boosting: gain is linear, but a recording that already reaches full scale has no headroom left. Boosting it just clips. The analysis panel reports peak level in dBFS and shows the exact gain needed to hit your target peak, so you can pick a number that works instead of guessing.
Two ways to work:
- Apply a manual gain in dB and preview the result
- Use the Normalize preset, which computes the gain for you from the target peak
What the limiter does: the output stage uses a leaky-integrator limiter at -0.1 dBFS. It catches brief overshoots created by gain rather than crushing the whole file, so loud passages stay controlled without flattening dynamics.
Export: WAV for editing, MP3 for sharing. Decoding, processing, and encoding all run in this browser tab. The file you select is not uploaded, and the rendered audio is not stored on any server.
Honest limits: this is gain and peak normalization, not loudness normalization against a broadcast standard such as LUFS. If you need EBU R128 or ATSC A/85 compliance for delivery, measure the exported file in a dedicated loudness meter before submitting it.
How It Works
Load a file
Drop an audio file, or the audio track of a video file, onto the workspace.
Read the levels
The analysis panel reports peak, RMS, crest factor, and the normalize gain.
Choose gain
Set a manual dB value or pick the Normalize preset and let the tool calculate it.
Render and export
Process, preview against the original, then download WAV or MP3.
Features
Measure First
Peak, RMS, crest factor, and the exact gain needed to reach your target peak.
Gain in dB
Apply up to +24 dB of clean gain and hear the result before you export.
Safety Limiter
A soft limiter at the output stage catches peaks rather than crushing dynamics.
Presets
Clean gain, Normalize, Podcast, and Loud master starting points.
Peak, RMS, and Why Both Matter
Peak level tells you the single loudest sample in the file. Average RMS tells you how loud the file feels overall. Crest factor is the difference between the two, and it is the number that explains why two files with identical peaks can sound completely different: a compressed master has a crest factor around 6 dB, while a quiet interview recording with a single door slam can measure 20 dB or more.
That distinction matters when you choose a boost. A file with a 20 dB crest factor has plenty of headroom to work with — raising it 8 dB brings the speech forward without touching the peak. A file that already has a 6 dB crest factor and a peak at -0.2 dBFS has nothing left; a boost of even 2 dB will start shaving transients. Read the measurements before you decide, and listen to the processed preview rather than trusting the numbers alone.
Limits, Export Formats, and Review
Every effect here is deterministic: the same file and the same control values produce the same output. That means you can reproduce a result later, but it also means the tool will not guess what you intended — check a short excerpt before rendering a long file, and keep the original.
MP3 export uses the same lamejs encoder as the rest of OfflineTTS, at 128, 192, or 320 kbps. Lossy encoding can push peaks slightly above the level you rendered, which is why the default target is -1 dBFS rather than -0.1 dBFS. If a downstream platform requires a strict true-peak ceiling, render WAV, measure it, and apply a small trim before encoding to MP3.
This tool processes level only. It does not remove noise, separate instruments, repair clipped samples, or identify content. For a noisy recording, run the noise remover first and boost afterwards — boosting a noisy file also boosts the noise floor, so cleaning before gain always produces a better result.
Related Tools
Tempo & Speed Changer
Slow down or speed up audio while holding the original pitch
Bass Booster
Add low-end weight with a shelf and a mud cut, not a blunt volume bump
Audio Equalizer
Ten bands from 32 Hz to 16 kHz, with presets and a spectrum view
Noise Remover
Learn the noise floor of a recording, then gate it out band by band
Volume Booster — FAQ
How much can I boost audio without distortion?
It depends entirely on the existing headroom. The analysis panel measures the current peak in dBFS; the difference between that and 0 dBFS is the maximum clean boost. The normalizer targets -1 dBFS by default, which leaves a small margin for lossy encoding.
Is this the same as loudness normalization?
No. This is peak normalization with a limiter. Loudness normalization targets an average level measured in LUFS, which streaming platforms use. Peak normalization makes a file as loud as it can be without clipping, which is what most single-file cleanup needs.
Does boosting add distortion?
Clean gain does not. Distortion appears only when the boosted signal exceeds full scale, which is why the output limiter exists and why the tool reports headroom before you apply gain. If the source already clips, no amount of gain repair is possible — the damaged samples are already in the file.
Can I normalize several files to the same level?
Yes — process them one at a time with the same target peak. The normalizer calculates gain per file, so every export lands at the same peak level.
Are my files uploaded?
No. Decoding, gain, limiting, and encoding all happen in this browser tab.
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