WAV to MP3 Converter

Encode a WAV into an MP3 roughly a tenth of the size, in your browser, at the bitrate you choose. This is the one direction where the conversion is genuinely worth making.

The converter is ffmpeg compiled to WebAssembly. It downloads once (30 MB) when you pick your first file, then stays in your browser cache.

A higher bitrate keeps more detail and costs more bytes. 192 kbps is transparent for most music on ordinary gear, 128 is plenty for speech, and 320 is the practical ceiling for MP3.

Your file is processed by your own browser and never uploaded. The engine itself is a one-time 30 MB download the first time you use it, and after that it comes out of your browser cache.

How to use WAV to MP3

  1. 1Drop your .wav files onto the box above, or click to pick them. Several at once is fine.
  2. 2Choose a bitrate. 320 kbps for music you care about, 192 kbps for general use, 128 kbps for speech.
  3. 3Play the result to check it, then download. A batch comes out as one .zip.

The good direction

Most format conversions are a compromise. This one mostly is not. A WAV holds uncompressed PCM, meaning every sample exactly as it was captured, with no codec having made any decisions about it yet. So to convert WAV to MP3 is to run a first-generation lossy encode, and lossy codecs are at their best when they can see the real waveform instead of the leftovers of somebody else's compression.

That is why the advice here is different from the advice on an M4A or OGG page. There, re-encoding stacks a second round of loss on top of a first. Here, there is only one round, and at a sensible bitrate the result is genuinely hard to distinguish from the source on normal playback equipment.

What you are trading

Size, for detail you probably cannot hear. Uncompressed stereo at 44.1 kHz and 16 bits costs about 10 MB per minute. The same minute at 320 kbps costs about 2.4 MB, and at 128 kbps about 1 MB. Nothing about the audio gets better in exchange, so the only question is how much you are willing to give up.

The parts of a mix that reveal MP3 first are the ones with the least structure for the encoder to model: cymbal decays, room reverb, crowd noise, breaths between words. Dense, loud material hides encoding artifacts well. Sparse, quiet material does not.

When to keep the WAV

Keep it if the file is a master, if it is going into a mix or an edit, or if anything downstream will re-encode it again. Every lossy pass compounds, and the right shape for an archive is a lossless original with lossy copies made from it as needed.

Files are read and encoded by your own browser. The engine is ffmpeg compiled to WebAssembly, downloaded once and then cached, so nothing about your audio travels over the network.

Frequently asked questions

How much smaller will the MP3 be?
About ten times, at 320 kbps. A 50 MB WAV becomes roughly 5 MB. At 128 kbps it is closer to twenty-five times. WAV stores every sample uncompressed, so almost all of that size is redundancy an encoder can remove.
Which bitrate should I pick?
320 kbps if the MP3 is the version people will actually listen to and you want no argument about quality. 192 kbps is transparent for most listeners on most equipment and saves 40 percent. 128 kbps is for speech, where higher rates buy nothing you can hear.
Is the quality loss noticeable?
At 256 or 320 kbps, almost never in normal listening. This is a first-generation encode from lossless material, which is the best case for any lossy codec: the encoder sees the real waveform rather than the residue of an earlier compression. Where it does show is cymbals, applause and reverb tails.
Does it keep the sample rate and bit depth?
The sample rate is kept, so a 48 kHz WAV becomes a 48 kHz MP3. Bit depth stops being a concept once you encode: MP3 does not store samples as integers at all, so a 24-bit source and a 16-bit source of the same audio produce very similar files.
Can it handle a long recording?
Up to 500 MB, which at CD quality is about 50 minutes of stereo. WAV files get large fast, so a full concert recording or a multi-hour interview may exceed that. Split it first if so.

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