MP3 Compressor
Compress MP3, WAV, M4A, and FLAC in your browser. Hit an exact file size, use a one-click voice preset, or tune the bitrate yourself. No uploads.
Good for shrinking podcasts, audiobooks, and voice memos to fit email or messaging limits.
▸▾Large files take time — keep the tab open
MP3 compression runs entirely in your browser using ffmpeg.wasm. Keep this tab open and active while it runs — closing or switching tabs will stall or stop processing. On iPhone and iPad, iOS limits memory per browser tab, so audio files over 100 MB may cause the page to restart. On Android, Chrome throttles background tabs which can stall long encodes. On desktop, a 500 MB audiobook can take 5–15 minutes depending on your CPU. Voice/podcast mode is dramatically faster than music-quality encoding because it uses a lower bitrate and a single channel.
Drop files or a folder here
or click to browse · paste from clipboard
Accepts .MP3, .WAV, .M4A, .AAC, .FLAC, .OGG, .OPUS · Up to 1,000 files
How it works
Drop your files
Drag and drop, click to browse, or paste from clipboard. Up to 1,000 files at once.
Choose settings
Adjust quality, format, and other options to match your needs.
Click Convert
Everything runs in your browser via WebAssembly. MP3 Compressor happens locally — no server involved.
Download
Download files individually or grab all at once as a ZIP.
Common target sizes
- 5 MBFit an MP3 under 5 MB for messaging apps, forum uploads, and lightweight email attachments.
- 8 MBHit the Discord free-tier upload cap. Drop the file, click compress.
- 16 MBFit an MP3 under WhatsApp's document limit. Send the audio without a Google Drive detour.
- 25 MBStay under Gmail's 25 MB cap. Send an MP3 as an attachment, not a Drive link.
Frequently asked questions
Yes. Drop WAV, M4A, AAC, FLAC, OGG, or Opus files and they'll be re-encoded to compressed MP3. No need to convert to MP3 first with a separate tool.
Turn it on for spoken-word content — podcasts, interviews, audiobooks, lectures, and voice notes. It forces 64 kbps mono at 22.05 kHz, which is transparent for speech and cuts file size by roughly 70–80% compared to a stereo music-quality MP3. Don't use it for music.
Quality preset picks a VBR tier (Small/Medium/High/Maximum) and lets the file size vary with audio complexity. Target file size hits an exact MB or KB by reading your file duration and computing the required bitrate. Custom bitrate gives you direct CBR or VBR control. Percentage shrinks each file to a share of its original bitrate — simplest, but the exact final size is approximate.
CBR (Constant Bitrate) holds one bitrate for the whole file — predictable size, slightly lower quality per kilobyte. VBR (Variable Bitrate) spends more bits on complex sections and fewer on quiet ones — better audio at the same average size, but the final file size varies with the source. Use CBR (or Target file size) when you have a hard ceiling like an email or Discord limit. Use VBR when archiving music.
Yes, by default. Artist, album, title, track number, year, genre, and embedded cover art are copied through to the output. You can disable this with the toggle if you want a stripped file.
There's no hard limit set by ConvertYard — you're only limited by your browser's memory. On desktop, 500 MB files compress reliably. On mobile (especially iOS), files over 100 MB may cause the tab to restart. For audiobooks and long recordings over 150 MB, a desktop browser is strongly recommended.
No. Compression runs entirely in your browser using ffmpeg.wasm. Your audio files never leave your device. Only the tool's code and the encoder library are downloaded from ConvertYard's servers.