Free volume booster, no upload.
Increase audio volume online without uploading anything, or normalize a batch of recordings so they all sit at the same loudness. This free volume booster measures the file the way your ears do — in LUFS, not just peaks — then raises it to the level you pick and limits the peaks so the result gets louder instead of clipping.
Add the recording that came out too quiet
Drag a file here, or press the button. Before you change anything, it is measured — properly, the way a broadcaster would measure it — and the numbers are shown to you.
MP3 · M4A · WAV · FLAC · Ogg · Opus · MP4 · MOV — even old AMR and WMA files. You can also paste one from the clipboard.
Your privacy — live proof, not a promise
- Files uploaded
- 0 bytes
- Processing
- Not started yet
- Your files
- Stay in this browser tab — gone when it closes
- Converter engine
- Not downloaded — only fetched if a format needs it
One download, and it isn’t your audio
Converting to MP3 or WAV needs no download at all. Less common formats use a built-in converter engine (32.5 MB) that comes from this site — not from some other company — downloads once, and is then saved in your browser. Your audio is never part of that download: the engine comes to your files, your files don’t go to it.
Don’t take our word for it: open your browser’s DevTools, watch the Network tab, then convert a file. You’ll see nothing carrying your audio — because this page has no upload feature at all. There is nowhere for your file to go.
Scope note, so this stays exact: the claim is about your files — they never leave this device. The site around it is not claim-free. It loads Vercel Analytics for aggregate page traffic, plus Google Analytics and Ads tags if you accept the consent prompt. Those measure page visits and store-link clicks. They never receive your audio, because nothing does. Full privacy policy.
Converted files are never stored by this page — they exist only in this tab until you download them.
The best fix for a quiet recording happens before it is made.
A boost raises the room noise along with the voice. BlackBox records continuously in the background so the microphone is already running when something worth hearing starts — no scramble, no distant first sentence. Free on iPhone and Android.
Honest limits of this page
- ·Boosting raises the background noise with everything else. It cannot un-record a bad room.
- ·Peaks are measured sample by sample, not as true peak — a fraction of a dB of inter-sample overshoot can survive.
- ·A recording that clipped when it was made stays clipped. Nothing can put back what was never captured.
- ·One file at a time, and the result is re-encoded.
Joining several recordings?
The audio joiner has the same loudness matching built into the merge, so you do not have to normalise each file by hand first.
Still hard to make out?
If volume was never the real problem, try transcribing it. Reading a difficult recording usually beats replaying it louder.
How the volume booster works without uploading anything
Other sites make you send them your file, do the work on their computers, and send it back. Your browser can do the same work itself — and your file is already here. That is the whole trick.
Add the quiet file
Drop it in. Before you touch anything, the page measures it: how loud it actually sounds in LUFS, where its loudest sample sits, and how much room there is above it.
Say how loud you want it
Pick a target — voice and podcasts at −16 LUFS, streaming at −14, broadcast at −23 — or type a plain dB boost if you would rather decide yourself. Peak normalisation is there too, for when you only want to fill the headroom.
The limiter catches the peaks
Boosting a recording with one door slam in it would clip everywhere else. A look-ahead limiter pulls the gain down just before each peak and lets it back up gently, so the file gets louder instead of distorted.
A/B it, then download
Switch between the original and the boosted version at the same moment in the audio to hear what changed. The new loudness and peak are shown as numbers too. Download MP3 or WAV.
Peak loudness is the wrong number
Most volume boosters do peak normalisation: find the loudest single sample, raise everything until it just fits. One door slam or one bumped microphone sets that sample, and the file comes back barely louder than it went in. It is the main reason 'increase audio volume online' so often does nothing.
LUFS is the number that matches your ears
Integrated loudness measures the whole recording through a filter shaped like human hearing, ignoring the quietest passages, and gives one figure in LUFS. It is what Spotify, YouTube and every broadcaster normalise to, and it is what this page measures — so 'make it as loud as a podcast' becomes an actual target of −16 LUFS rather than a vibe.
The limiter is why boosting works here
Once you raise a quiet recording by 12 dB, its few loud moments no longer fit. Clipping them makes the crunch people associate with amplified audio. The limiter here looks a few milliseconds ahead, pulls the gain down before each peak arrives and lets it back up over sixty milliseconds, so peaks are contained without the pumping you get from clamping.
What people use it for
Rescue a recording made too far from the microphone
The commonest problem with phone recordings. A 12–15 dB boost with limiting makes most of them usable again.
Match a set of recordings
Normalise each one to the same LUFS target and they sit at the same level, whatever they were recorded at.
Prepare a podcast episode
−16 LUFS with peaks under −1 dBFS is the standard most podcast platforms expect, and it is one click here.
Make a recording audible on a phone speaker
Small speakers have no low end and little power. Raising loudness rather than peaks is what makes the difference.
A recording that needed 15 dB of boost was recorded too quietly. Check the mic settings before the next one.
Volume booster — your questions, answered
How do I increase the volume of an audio file online?+
Drop it onto this page, choose a loudness target or type a dB boost, and download the result. The measuring, boosting and limiting all happen in your browser, so the file is never uploaded and there is no account or size cap.
Why did other volume boosters barely make my file louder?+
Most of them only do peak normalisation: they find the single loudest sample and raise everything until it just fits. If your recording has one thump in it, that thump uses all the headroom and nothing else moves. This page measures perceived loudness in LUFS instead, which is what actually needs raising.
What is LUFS, and which target should I pick?+
LUFS is loudness as your ears weigh it, averaged over the whole recording. Use −16 LUFS for voice, podcasts and voice notes; −14 to match Spotify, YouTube and Apple Music; −23 for EBU R 128 broadcast delivery. If you just want it as loud as a phone speaker will carry, there is a setting for that too.
Will boosting make my audio distort?+
Not here. A look-ahead limiter sees each peak a few milliseconds before it arrives, ducks the gain, then releases it gently, so the peaks stay under a −1 dBFS ceiling. Boosting without a limiter is what produces the crunchy result people expect.
Can this fix a recording that is already distorted?+
No. If a recording clipped when it was made, the waveform was flattened at the moment of capture and that detail was never stored. Raising or lowering it afterwards moves the damage around but cannot undo it. No tool can, whatever it claims.
Can I make several recordings the same loudness?+
Yes, one at a time: normalise each to the same LUFS target and they will match, because the target is an absolute scale and not a relative adjustment. If they are going into one file, the audio joiner has loudness matching built into the merge.
Is this volume booster free, and is anything uploaded?+
It is free with no account, no watermark and no size limit, and nothing is uploaded. Measurement and processing run in this browser tab, which is also why it works with the network disconnected.
The rest of the audio toolkit
Also here: the audio converter, the compressor, the transcriber and the browser voice recorder. All free, all on your device.
Record your whole day, privately.
BlackBox is a 24/7 background voice recorder with scheduling, on-device transcription and local storage — about 14 MB an hour. Free on iPhone and Android.