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MP3 — or WAV, M4A, OGG, FLAC. Made louder in your browser, never uploaded.Video and audio are processed in your browser by FFmpeg (ffmpeg.wasm), free software under the GPL-2.0-or-later and MIT licenses — licenses & source.
About the MP3 volume booster
Some MP3s are just too quiet: a lecture recorded from the back of the room, an old song, a voice memo, a podcast you cannot hear in the car. Turning up the speaker does not always help, because the phone or the car is already at the top.
This tool makes the file itself louder. You choose the boost in decibels (dB) — it starts at +6 dB — and the tool writes a new MP3 that keeps that boost wherever you play it.
Everything happens in your browser. Your MP3 is never uploaded.
Features
- Boost up to +20 dB — opens on +6 dB, which doubles the signal
- See the room you have — the loudest point is measured before you change anything
- Limiter — on by default; it holds the loudest peaks at −1 dB instead of letting them crackle
- Boost to the maximum — lifts the whole file until its loudest point reaches a target
- MP3 stays MP3 — about the same bitrate as before; WAV, M4A, OGG and FLAC keep their format too
- Fade in and out — optional, for a clean start and end
- Private — the file is changed on your device, never uploaded
What the dB numbers mean
A boost in dB multiplies every sample by the same number. The tool shows both:
| Boost | Signal × | How it sounds |
|---|---|---|
| +3 dB | 1.41 | a little louder |
| +6 dB | 2.00 | clearly louder (the start value) |
| +10 dB | 3.16 | about twice as loud to most ears |
| +12 dB | 3.98 | much louder |
| +20 dB | 10.00 | ten times the signal — only for very quiet files |
The "Signal ×" numbers are exact: 10 to the power of (dB ÷ 20). "How it sounds" is a rule of thumb — ears do not hear in straight numbers.
How much can you boost?
The loudest sound an MP3 can hold is 0 dB. Everything is measured below that, so a quiet file shows a number like −14 dB. The tool reads the loudest point of your file first. The room you have is simply the difference to −1 dB:
| Loudest point now | Boost | Loudest point after | What happens |
|---|---|---|---|
| −14 dB | +6 dB | −8 dB | clean — lots of room left |
| −14 dB | +13 dB | −1 dB | clean — the most without limiting |
| −8 dB | +6 dB | −2 dB | clean |
| −4 dB | +6 dB | would be +2 dB | the limiter holds the peaks at −1 dB |
| −4 dB | +6 dB, limiter off | would be +2 dB | the peaks are cut at 0 dB and crackle |
The page shows the "after" number as you move the slider, and warns you when a setting goes past the maximum.
Honest notes on boosting
- A boost cannot add detail. It makes everything louder by the same amount — the voice, and also the hiss, the hum and the room noise.
- Too much boost distorts. When the loudest parts go past the maximum, they are cut flat, and you hear a crackle or a buzz. That is why the limiter is on.
- The limiter is not magic. It turns the loudest peaks down for a moment. With a big boost on a file that is already loud, it works hard, and the sound gets flatter and more tiring. A smaller boost always sounds cleaner.
- Peak is not loudness. One loud cough can sit at the top while the rest stays quiet. Cut it out first with the MP3 Cutter, then boost.
What people use it for
- A lecture or meeting recording that came out too quiet
- An old song or a digitised tape that is much quieter than new music
- A podcast or audiobook you cannot hear in the car
- A voice memo or interview for a video
- A ringtone or alarm sound that is too soft
Frequently asked questions
Does boosting the volume lower the quality?
The MP3 is decoded and encoded once more, at about the same bitrate, so it loses a tiny bit. You will not hear that. What you can hear is a boost that is too big: crackle without the limiter, or a flat, squashed sound with it.
What is the best boost to choose?
Start with +6 dB and press "Boost the volume". If it is still too quiet, go higher, but watch the "after" number. Or choose Boost to the maximum and the tool works out the boost for you.
Why is my MP3 still quiet after boosting?
Probably one short loud sound (a clap, a cough) is already near the top, so the rest cannot go up without limiting. Cut that sound out, or use a bigger boost with the limiter on.
Is my file uploaded?
No. The file is measured and changed inside this page, on your own device. It never reaches a server.
Related tools
- Change Audio Volume — make audio louder or quieter, in percent
- Bass Booster — boost only the low notes
- MP3 Cutter — cut out a loud sound before boosting
- Remove Background Noise — take out the hiss first
- Merge MP3 — join several MP3 files into one
How to use it
- Click Click to upload, or drag your MP3 onto the box
- Read the loudest point now — it tells you how much room there is
- Move the Boost slider (it starts at +6 dB), or choose Boost to the maximum
- Keep the limiter on, and watch the "after" number
- Press Boost the volume, listen, then click Download the louder file
