A WAV file is audio stored with nothing thrown away. That is exactly why it is useful in an editor and exactly why you cannot email it: at the usual CD settings (44.1 kHz, 16-bit, stereo) a WAV runs at 1,411 kbps, which is about 10 MB for every minute. Three minutes is 30 MB. An hour is roughly 600 MB.
Converting it to MP3 is how that becomes sendable. Here is the whole procedure, then the parts worth understanding before you run it.
The three steps
- Open the WAV to MP3 page. Nothing downloads yet; landing on the page costs you a stylesheet and two fonts.
- Drop your WAV into the bay, or press Load file and pick it. The screen shows what it found: source format, output format, file size, and length. If those numbers do not match the file you meant, you loaded the wrong one.
- Press the red Convert key. The meter reports real progress. When it finishes, the MP3 is in your downloads folder.
The first time you convert anything, there is one extra wait. The converter itself, a 32 MB WebAssembly build of ffmpeg, has to download before it can run. It is fetched only once you have actually chosen a file, so browsing the site never pays for it, and it is cached afterwards. Every conversion after the first starts immediately.
What the conversion costs
MP3 is lossy. It makes files smaller by discarding detail the encoder judges you will not notice, and the discarded part does not come back. That is the trade, and it is worth stating in numbers rather than adjectives:
| Three minutes of audio | Size | Compared to WAV |
|---|---|---|
| WAV, 44.1 kHz 16-bit stereo | 30 MB | — |
| MP3 at 320 kbps | 7.2 MB | about a quarter |
| MP3 at 192 kbps | 4.3 MB | about a seventh |
| MP3 at 128 kbps | 2.9 MB | about a tenth |
For music you intend to listen to, 192 kbps is the sensible default and the point where most people stop hearing a difference. For speech (an interview, a lecture, a voice memo) 128 kbps is already generous. If the WAV is a master and the MP3 is what your listeners will actually hear, spend 320. The bitrate guide goes through this properly, including what variable bitrate changes.
Keep the WAV
You can convert the MP3 back to WAV later, and the file will genuinely be uncompressed again. But it will contain only what survived the MP3. Nothing the encoder discarded is recoverable, by any tool. The WAV is your master copy. Converting does not modify it, so keeping it costs you nothing but disk space.
Why this one does not upload your file
Most converters work by uploading your audio to a server, converting it there, and sending it back. That is why they have size caps — Zamzar stops at 25–50 MB, FreeConvert at 1 GB — and why they ask you to sign up.
This page converts inside your browser instead. The file is read from disk by the page, decoded and re-encoded in memory on your own device, and written back to your downloads. It is never transmitted, so there is no upload wait, no queue, no account, and no size rule beyond how much your browser can hold at once. On a WAV of a few hundred megabytes, a laptop copes more comfortably than a phone. That is the real limit, and it is the only one.
You do not have to believe any of that. Open your browser's developer tools, switch to the network panel, and convert something: the converter downloads once, and no request carries your audio. Are online audio converters safe? goes into what you are actually agreeing to when you use the other kind.
If something goes wrong
- "Out of memory." The file is larger than this browser can hold at once. A desktop browser will usually manage it, or convert a shorter section.
- "Could not read this file." The contents did not decode. Usually the extension does not match what is actually inside, or the file is truncated.
- "The engine could not start." The 32 MB converter did not finish downloading. Check the connection and press Convert again; it resumes from the cache.
Once the converter is cached, the page keeps working with the network off entirely. That is a reasonable thing to test if you want to be sure nothing is being sent.