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WAV to MP3

Shrink bulky WAV recordings to MP3 at the bitrate you choose, entirely in your browser.

Processed on your device, nothing uploadedLast updated

To convert WAV to MP3, drop the WAV file into the WAV to MP3 tool, choose an MP3 bitrate, click Convert to MP3 and download the file. FFmpeg encodes the audio with LAME at 128, 192, 256 or 320 kbps; 192 kbps is transparent for most listeners and makes the file about ten times smaller than the WAV.

Your file stays in this tab.On your device
Options
Add several files to get a single ZIP back.

FFmpeg (about 30 MB) is downloaded once on first use and cached by your browser. Speed depends on your device.

How do I convert WAV to MP3?

  1. Drop your WAV files onto the drop zone, or click to browse.
  2. Choose an MP3 bitrate: 128 kbps (small) for speech, 192 kbps (good) for music, 256 kbps or 320 kbps (best) if you want extra headroom.
  3. Click Convert to MP3.
  4. Wait a few seconds per file while LAME encodes the audio.
  5. Download each MP3, or Download all as ZIP when you converted a batch.

WAV stores raw PCM samples, about 10 MB per minute for CD-quality stereo, which is why a two hour recording weighs over a gigabyte. This tool passes each file through FFmpeg's LAME encoder (libmp3lame) at the constant bitrate you choose. At 128 kbps the MP3 is about 1 MB per minute, at 192 kbps about 1.4 MB, and at 320 kbps about 2.3 MB, so even the highest setting is a 4 to 5 times reduction and the default is closer to ten.

Choose the bitrate by what is in the file. Speech, lectures, interviews and voice notes are fine at 128 kbps. For music, 192 kbps is transparent for most listeners on most equipment, and it is the setting to pick if you are not sure. 256 and 320 kbps buy a small margin for critical listening on good headphones, or for a file you may later edit and re-encode; going from WAV, they are the closest MP3 gets to the original.

MP3 encoding is fast even in a browser. A 5 minute track finishes in a few seconds on a recent laptop and in perhaps 20 to 30 seconds on a phone; a 90 minute recording takes a minute or two. Batch mode encodes every file you drop in and offers them together as a ZIP. Stereo and mono are both preserved, and 24-bit or 96 kHz WAVs are converted to 16-bit at 44.1 or 48 kHz before encoding, which is all the MP3 format supports.

Everything runs in your browser using FFmpeg compiled to WebAssembly, downloaded once (about 30 MB) and cached for later visits. No audio is uploaded, so the file size limits that free online converters impose do not apply here. Files up to about 1 GB are comfortable; the browser's roughly 2 GB WebAssembly memory limit is the ceiling, so split a very long session into a few files if it fails.

How it works: this tool uses FFmpeg compiled to WebAssembly (ffmpeg.wasm), loaded into your browser. No server is involved, so Kilnfile never sees your file. Last reviewed 20 September 2026.

Frequently asked questions

Does WAV to MP3 lose quality?

Yes, MP3 is a lossy format and discards detail that most people cannot hear. At 192 kbps the difference from the WAV is inaudible to nearly everyone in a blind test; at 128 kbps trained ears may notice on cymbals and dense mixes. Keep the WAV if you may need to edit later.

Which bitrate is best for music?

192 kbps is the sensible default and sounds transparent to most listeners. Choose 320 kbps if storage is not a concern and you want the maximum the format allows. 128 kbps is better suited to speech.

How much smaller will the file be?

About ten times smaller at 128 kbps, seven times at 192 kbps and four to five times at 320 kbps compared with 16-bit 44.1 kHz stereo WAV. A 50 MB WAV becomes roughly 7 MB at 192 kbps.

Can I convert a lot of WAV files at once?

Yes. Drop in as many as you like and they are encoded one after another. When more than one has finished, a Download all as ZIP button appears next to the individual downloads.

Is my recording uploaded?

No. The WAV is read into your browser's memory, encoded by FFmpeg running as WebAssembly, and the MP3 is saved to your device. Nothing touches a server, and there is no signup or watermark.

Cite this page: “WAV to MP3 Converter, Free and No Upload”, Kilnfile, https://kilnfile.com/media/wav-to-mp3/

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