How much smaller will the file be?

Roughly a tenth at High quality. A 60 MB WAV becomes about 6 MB, and Low quality is about a third of that again.

Which quality should I pick?

High for music — it is transparent for nearly everyone. Low with mono for speech, which sounds the same on a voice and is roughly a third the size.

Is the encoder any good?

It is LAME, the reference open-source MP3 encoder that desktop software has used for two decades, compiled to WebAssembly.

Are the WAV tags kept?

No. WAV and MP3 use different metadata systems. Add ID3 tags afterwards if you need them.

No. The demuxing, decoding and encoding all happen in this tab using the browser’s own media stack plus a WebAssembly encoder. A recording can be an interview, a lecture, a private call — none of it is transmitted. Turn your Wi-Fi off after the page loads and it still works.

How large a file can I convert?

There is no imposed limit, only your device’s memory — around 2 GB in a desktop browser and 400 MB on a phone, since the file is held in memory while it converts. A two-hour video converts in well under a minute on a laptop.

Can I convert several files at once?

Yes. Drop as many as you like, or a whole folder. Each keeps its original name with the new extension, and you can download them individually or as a ZIP.

WAV to MP3 Converter — LAME Encoding, No Upload

Compresses uncompressed WAV audio into MP3, typically around a tenth the size. Nothing is uploaded — LAME is compiled to WebAssembly and runs in this tab.

How MP3 encoding works without a server

Browsers decode MP3 but do not encode it — there is no MP3 encoder in WebCodecs. The encoding here is LAME, the reference open-source MP3 encoder, compiled to WebAssembly and loaded only when you actually convert to MP3.

It is the same encoder desktop software has used for twenty years, producing standard files that play everywhere. Because it is fetched on demand, pages that convert to WAV or M4A never download it.

This is the first lossy generation

Unlike most conversions on this site, the source here is lossless. That means the MP3 is the first lossy encode, which is the best case: the encoder is working from the full signal rather than from something already degraded.

At High quality the result is transparent to almost everyone on almost all material. Keep the WAV as your master and treat the MP3 as a distribution copy — you can always make another MP3 from the WAV, but you can never get the WAV back from the MP3.

Choosing the settings

Music: High quality, keep stereo, keep the sample rate.

Speech — a podcast, an interview, a lecture: Low quality with mono selected. Low alone is about a third the size of High; mono is what makes Low sound fine on a voice.

Anything going to a broadcaster or a distributor: check their spec. Many require a specific bitrate and sample rate, and some still require 44.1 kHz.

What about the WAV metadata

WAV files can carry LIST/INFO chunks and Broadcast Wave metadata. Those do not survive into the MP3, which uses ID3 tags instead. If your workflow depends on embedded metadata, add the ID3 tags afterwards in a tagging tool.

Other names for this

Also searched as “convert wav to mp3”, “wav to mp3 high quality”.

Questions

How much smaller will the file be?: Roughly a tenth at High quality. A 60 MB WAV becomes about 6 MB, and Low quality is about a third of that again.
Which quality should I pick?: High for music — it is transparent for nearly everyone. Low with mono for speech, which sounds the same on a voice and is roughly a third the size.
Is the encoder any good?: It is LAME, the reference open-source MP3 encoder that desktop software has used for two decades, compiled to WebAssembly.
Are the WAV tags kept?: No. WAV and MP3 use different metadata systems. Add ID3 tags afterwards if you need them.
Is my file uploaded?: No. The demuxing, decoding and encoding all happen in this tab using the browser’s own media stack plus a WebAssembly encoder. A recording can be an interview, a lecture, a private call — none of it is transmitted. Turn your Wi-Fi off after the page loads and it still works.
How large a file can I convert?: There is no imposed limit, only your device’s memory — around 2 GB in a desktop browser and 400 MB on a phone, since the file is held in memory while it converts. A two-hour video converts in well under a minute on a laptop.
Can I convert several files at once?: Yes. Drop as many as you like, or a whole folder. Each keeps its original name with the new extension, and you can download them individually or as a ZIP.