WAV to MP3 Converter

About the WAV to MP3 Converter

Turn WAV recordings — 16-bit, 24-bit and 32-bit PCM, 32- and 64-bit float, and Broadcast WAV (BWF) from field recorders and studios — into MP3 files that are a fraction of the size. Choose a constant bitrate up to 320 kbps or a LAME variable-bitrate level, and optionally make the MP3 mono or 44.1 kHz to save more space.

The WAV’s own metadata is read and carried into the MP3’s ID3 tags: the RIFF INFO title, artist, album, date, genre, comment, copyright and track, and from a Broadcast WAV the description and recording date and time. The page shows everything it found, including BWF fields such as originator, timecode and coding history, before you convert.

You can trim and fade the MP3, add cover art, and convert a whole folder of WAVs at once. Nothing is uploaded: the WAV is read and encoded with LAME in your browser.

How much smaller, and which settings?

CD-quality WAV (16-bit, 44.1 kHz, stereo) is 1,411.2 kbit/s, about 10.6 MB a minute. An MP3 at 320 kbps is about 2.4 MB a minute (23 % of that), 192 kbps about 1.4 MB (14 %) and 128 kbps about 0.96 MB (9 %). A 24-bit 96 kHz WAV is over three times larger again.

• Music: 320 kbps CBR, or VBR -V 0 (LAME’s “extreme” preset, typically about 245 kbps on music) or -V 2 (its “standard” preset, about 190 kbps).
• Speech, interviews, podcasts: Mono at 64–96 kbps, or VBR -V 5 (about 130 kbps on music, much less on speech).
• Sample rate: MP3 stores at most 48 kHz (ISO/IEC 11172-3), so 88.2 kHz becomes 44.1 kHz and 96 or 192 kHz become 48 kHz unless you choose otherwise. The page resamples with a band-limited windowed-sinc filter, so ultrasonic content in hi-res files cannot fold back into the audible range as false tones.

Which WAV files work

WAV is the RIFF/WAVE format from Microsoft and IBM’s Multimedia Programming Interface and Data Specifications 1.0. This page reads PCM at 8, 16, 24 and 32 bits, IEEE float at 32 and 64 bits, A-law and µ-law, the WAVE_FORMAT_EXTENSIBLE header used for 24-bit and multichannel files, and RF64 for recordings over 4 GB.

Some “WAV” files hold compressed audio instead — IMA or Microsoft ADPCM, GSM, or even MP3 in a WAV wrapper. Browsers have no decoders for those, so the page names the codec and suggests exporting the file again as PCM WAV. Multichannel WAVs are mixed down to stereo, because MP3 holds at most two channels.

Broadcast WAV and INFO tags

A Broadcast WAV (EBU Tech 3285) adds a “bext” chunk: a description of up to 256 characters, the originator (often the recorder or studio), a reference, the date and time of the recording, a time reference (the timecode as a sample count since midnight), loudness values in version 2, and the coding history. RIFF INFO chunks hold the title (INAM), artist (IART), album or product (IPRD), date (ICRD), genre (IGNR), comment (ICMT) and copyright (ICOP); many editors also write a track number (ITRK).

INFO tags are used first; the BWF description fills in the title when there is none (the standard recommends a summary in its first 64 characters), and the origination date and time become the ID3v2.4 recording date (TDRC). Recorder take data such as “sSCENE=12” and “sTAKE=3” becomes a title like “Scene 12, take 3”.

Limitations

• Compressed WAV files (IMA/Microsoft ADPCM, GSM, MP3 or WMA inside WAV) and Sony Wave64 (.w64) files cannot be read.
• BWF timecode, coding history, iXML data, markers, cue and loop points stay in the WAV: MP3 has no standard fields for them.
• MP3 is lossy. Keep the WAV for editing and archiving; the MP3 is for listening and sharing.
• Multichannel WAVs are mixed down to stereo, and 32-bit float samples above full scale are limited to full scale in the MP3.
• Very long WAVs need time and memory, especially on phones; the result is kept in memory until you download it.

Privacy

Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot. The audio engine and the LAME MP3 encoder download from MySmartCoPilot the first time you use them (about 2.4 MB more for variable bitrate). Your recordings are never uploaded.