Compress an audio file for email, Discord, WhatsApp — or any upload limit.
Drop an MP3, WAV, M4A, FLAC or OGG. Pick a target bitrate (lower = smaller), optionally downmix to mono for another ~50% off. We re-encode it right here in your browser. Your file never touches a server, and there's no daily quota or "Pro" wall.
drop audio here
MP3, WAV, M4A, FLAC, OGG, AAC. Drop several for batch.
Compress for a specific upload limit
Different platforms cap attachments at different sizes. Pick the bitrate that gets you under the line for what you're sending:
- Gmail / Outlook attachment — 25 MB max. A 30-minute podcast at 96 kbps mono is ~21 MB. At 64 kbps mono, ~14 MB.
- Discord free upload — 10 MB. Use 64 kbps mono for voice clips, 96 kbps stereo for short music clips. Cut the file first with Audio Cutter if it's still too big.
- Discord Nitro Basic — 50 MB. 128 kbps stereo handles ~50 min of music.
- Discord Nitro — 500 MB. No realistic concern for audio.
- WhatsApp voice clip — ~16 MB. Most voice messages already fit, but a long sermon or lecture WAV needs to go to 96 kbps mono MP3 first.
- Slack free — 1 GB. Compression mostly a courtesy here, not a requirement.
- Anchor / Spotify for Podcasters upload — 250 MB. Easy at 128 kbps stereo for episodes under 4 hours.
- SMS / iMessage attachment. Carriers vary, but under 1 MB is the safe bet — drop to 32 kbps mono for short voice clips.
How much can you shrink it?
It depends on what you started with. A 1-hour WAV recording is ~600 MB. The same hour at 128 kbps MP3 mono is ~28 MB — about a 95% reduction with no audible loss for voice. Music is more sensitive: 192 kbps stereo MP3 is usually indistinguishable from CD for casual listening, and 128 kbps stereo MP3 is fine for streaming over poor connections.
Picking a bitrate
- 64 kbps mono — speech, audiobooks, voicemail; tiny.
- 96–128 kbps — podcasts, voice-heavy content.
- 128–160 kbps — casual music listening, web embeds.
- 192 kbps — music you actually care about, but not lossless.
- 256–320 kbps — premium music; barely worth it over 192 for most ears.
FAQ
How do I compress an MP3 to under 25 MB for Gmail?
Drop the file, pick 96 kbps mono, and most hour-long voice recordings come out around 21 MB. If it's still too big, drop to 64 kbps or trim with the cutter first.
How do I compress audio for Discord's 10 MB limit?
For voice clips, 64 kbps mono fits ~20 minutes under 10 MB. For music, you'll usually need to trim — a typical 3-minute song at 128 kbps stereo is ~3 MB, comfortably under.
How do I send a WhatsApp voice note as a standard MP3?
WhatsApp uses the OPUS codec, not MP3. Save the .opus file out of WhatsApp, drop it here, pick MP3 at 96 kbps. For batches of WhatsApp voice notes, see our OPUS to MP3 page.
Will compressing an MP3 again make it worse?
Slightly — every lossy re-encode loses some fidelity. If you have the original WAV, compress that instead. If all you have is the MP3, the difference at 128 kbps and above is usually inaudible on consumer speakers.
Can I compress to WAV?
WAV is uncompressed by definition — there's no bitrate to lower, only the sample rate and bit depth. To meaningfully shrink a WAV you have to encode to a compressed format like MP3 or OGG.
What bitrate for a podcast upload?
128 kbps stereo is the unofficial standard. 96 kbps mono is fine for pure voice and cuts size by ~40%. Most podcast hosts (Anchor, Buzzsprout, Transistor) accept up to 250 MB per episode.
Does this work offline?
Once the page has loaded, yes. You can disconnect from the internet and the tool still works.
What's the size limit?
Around 500 MB per file on a typical laptop. Browser memory is the bottleneck.