Increase audio volume online — up to 500%, nothing uploaded

What "boost the volume" really means

Digital audio has a hard ceiling. Every sample sits somewhere between −1 and +1, and full scale is full scale — there is nothing above it. Boosting volume means multiplying every sample by some number: at 200 % each sample doubles, at 300 % it triples. That works beautifully right up until a sample that was already at 0.6 gets multiplied to 1.8, at which point it cannot be represented, gets flattened to 1.0, and the smooth top of the waveform turns into a flat plateau. Flat plateaus are what distortion sounds like.

This is why so many volume boosters disappoint. They will happily multiply by four and hand you back something that is louder and also crunchy. The interesting question is never "how much can I multiply by" — it is "how much headroom does this particular file have", and that varies enormously. A modern pop master is already squeezed against the ceiling and has almost none. A voice memo recorded across a room might peak at −24 dBFS and have 24 dB of room to grow — about 16× in amplitude. This slider stops at 5× (+14 dB), so a file that quiet takes two passes: boost it, save a 32-bit float WAV, load that back in and boost again.

Smart Boost: the number that is actually true for your file

When you load a file, this tool scans every sample in every channel and reports the loudest peak in dBFS, the average level (RMS), the integrated loudness in LUFS, the headroom before clipping, and the largest volume percentage that keeps every sample under full scale. That last number is what Smart Boost applies.

Crucially, the headroom figure accounts for whatever the equalizer and bass controls are doing, not just the raw file. Those stages come first in the chain and can add more than 20 dB between them, so a reading based on the untouched file would be badly wrong the moment you moved a slider. Change a band and the numbers are re-measured through the real processing chain.

It is worth trying that button before you touch anything else. If it says 340 %, your file was quiet and you can have all of that loudness for free — no compromise, no artefacts, mathematically identical audio just scaled up. If it says 104 %, your file is already about as loud as the format allows, and the honest answer is that a volume slider is the wrong tool: what you want is the equalizer to bring forward the frequencies you are struggling to hear, or the limiter below to buy a few more decibels of perceived loudness.

The limiter, and why louder-than-safe can still sound fine

Leave the limiter switched on and you can push past the safe number without the file falling apart. Instead of chopping peaks off square, the limiter bends the very top of the waveform smoothly toward the ceiling — the loud parts get quietly compressed while everything below the threshold passes through untouched. You trade a little dynamic range for real loudness, which is exactly the trade mastering engineers make on every record you own.

It is not magic, and the tool will tell you when you are asking too much. Push a heavily-limited pop track to 400 % and the warning under the sliders will say what percentage of the file is running past full scale and what a sensible ceiling would be. Believing that warning will get you a better result than ignoring it.

Which files this works on

Anything your browser can decode: MP3, WAV, M4A, AAC, OGG, Opus, and usually FLAC. Chrome, Edge, Safari and Firefox all handle the common formats. A few older or unusual containers — WMA, AMR, some FLAC variants — are decoded by some browsers and not others, and if yours cannot manage it you will get a plain message saying so rather than a silent failure.

Export is WAV, which is uncompressed. That means the download is large — roughly 10 MB per minute of stereo CD-quality audio — but it also means nothing is thrown away in a second round of lossy encoding. If you need a smaller file afterwards, re-encode it once, at the end, when you are happy with the level.

What this cannot do

It cannot raise your device's system volume. Nothing running in a browser tab can, and on iOS nothing running in any app can either — that is an operating system restriction, not a missing feature. What this tool does is make the file itself louder, which then plays louder everywhere: in your car, on a Bluetooth speaker, in a video editor, on someone else's phone. That is usually what people actually needed.

It also cannot rescue a recording that is fundamentally broken. Boosting a quiet recording boosts its hiss along with everything else, so a whispered voice memo taken in a windy street gets louder and noisier. Getting close to a decent microphone at record time is worth more than any amount of processing afterwards.