WAV is a container for uncompressed PCM. A three-minute stereo recording at 16-bit 44.1 kHz is about 30 MB. That is ideal while you still edit. It is a poor way to email the same take.
MP3 throws away parts of the spectrum a person is unlikely to notice, then entropy-codes the rest. You cannot turn an MP3 back into the original WAV. Keep the WAV if you might remix later.
A simple chart
- Voice memo, language lesson — 96 or 128 kbps, mono
- Podcast you still care about — 128 or 192 kbps stereo
- Music for a playlist — 192 kbps
- Archival “good enough” music — 256 or 320 kbps
This page never sees the samples. If you need a format other than MP3 (AAC, Opus), use a desktop encoder. LAME in the browser is here for the common “this WAV will not fit in the chat” case.