MP3 to WAV
Decoded once and stored as it is — with the size stated up front.
Runs locallyDrop files here, or click to choose
Accepts MP3. Up to 300 MB and 30 minutes on this device, no sign-up.
Choose a file and this page decodes it first — sample rate, channel count and peak level — and shows the exact size of the WAV before anything is written. Limits on this device: 300 MB per file and 30 minutes of audio. Nothing is uploaded at any point.
This page decodes your MP3 and writes the samples straight out as a 16-bit PCM WAV, at the sample rate the file was recorded at. Nothing is compressed a second time. The file will get considerably larger, and the exact figure appears before you press anything, because that is the whole trade you are making here.
What this conversion does, precisely
An MP3 stores audio as a series of compressed frames. Decoding turns those frames back into a list of samples — the actual numbers describing the waveform. A WAV file stores that list with almost no ceremony: a 44-byte header saying how many channels there are, how many samples per second, and how many bits each sample uses, followed by the samples themselves.
So the conversion is a decode followed by a write. Nothing is compressed on the way out, which is why there is no quality slider on this page — there is no quality decision to make.
What it does not do is improve the audio. This is the single most common misunderstanding about converting a lossy format to an uncompressed one, and most converter sites are content to leave you with it. The detail an MP3 encoder discarded is gone permanently; storing what remains in a bigger file preserves it exactly, including the compression artefacts. That is why this page does not use the word lossless about the result. No second lossy pass happens, and that is a real and useful guarantee, but it is a different claim.
The size, in numbers you can plan around
Uncompressed 16-bit PCM at 44.1 kHz in stereo is 176,400 bytes per second — about 10.1 MB per minute. A four-minute song that was 4 MB as a 128 kbps MP3 becomes roughly 40 MB. A 48 kHz stereo file is about 11.0 MB per minute; mono halves it.
That is a tenfold increase for no gain in quality, which is why converting to WAV is only worth doing when something downstream requires it. This page shows the exact output size and the multiple over your source before you start, so the decision is made with the number in front of you.
If you want a smaller file and better compatibility than MP3 gives you, converting to WAV is the wrong move — it is bigger, and it fixes nothing. If you want to send audio to someone with limited bandwidth, keep the MP3.
When you genuinely need a WAV
When software demands it. Plenty of tools accept only uncompressed PCM: game engines, telephony and IVR systems, some broadcast and radio automation, older samplers and hardware, certain scientific and speech-analysis packages, and a surprising number of upload forms for voice prompts.
When the audio is about to enter an editing chain. Editors decode to PCM anyway; giving them a WAV means each intermediate save is not another round of MP3 loss stacked on the last. Convert once at the start, edit as much as you like, and export to a compressed format at the end.
When you need sample-exact access. Analysis, alignment, splicing at precise positions and generating waveforms all work on samples, not frames. An MP3 frame is about 26 milliseconds long and the frame grid rarely lines up with anything you care about.
The sample rate trap, and why nothing is uploaded
There is a mistake that is easy to make when building this tool and impossible to notice as a user. A browser decodes audio at whatever rate the audio context was created with, which on most desktops is 48,000 samples per second. Decode a 44.1 kHz MP3 that way and the result has been resampled — the file is valid, it plays, the length is right, and the tool has quietly changed the audio while claiming not to have touched it.
This page reads the sample rate out of the MP3 frame header first and decodes at exactly that rate, so no resampling happens. It reports the rate it used, and if a header cannot be read it says which rate it fell back to rather than letting you assume the number came from your file.
None of this involves a server. Decoding is done by your browser and the WAV is assembled in the tab, so nothing is uploaded: open your developer tools, watch the Network tab and convert a file. The Content-Security-Policy this site sends restricts connections to our own origin and your browser enforces it. No account, no queue and no watermark. The limits that do exist come from your own device rather than from us, and the page states them before you start: 300 MB per file and 30 minutes of audio on a desktop, half on a phone. After the first visit the page works offline.
Frequently asked questions
Does converting MP3 to WAV improve the sound?
No. What the MP3 encoder discarded is gone for good. A WAV stores what remains exactly — artefacts included — in a much larger file.
How much bigger will the file be?
About 10.1 MB per minute at 44.1 kHz in stereo, which is roughly ten times a typical 128 kbps MP3. The page shows the exact size and the multiple before you start.
Is the result lossless?
No second lossy compression happens, which is the useful guarantee. But lossless would mean nothing was ever lost, and your MP3 had already lost detail before it reached us.
Will the sample rate change?
No. The rate is read from the MP3 header and used for decoding, so a 44.1 kHz file stays at 44.1 kHz. If the header cannot be read, the page tells you which rate it used instead.
Why 16-bit and not 32-bit float?
Because 16-bit PCM is the WAV variant that every player, editor and device reads. Float WAVs are twice the size and a fair amount of software cannot open them.
Is my file uploaded?
No. Both the decoding and the WAV writing happen in your browser tab. You can verify it in the DevTools Network tab while converting.