Compress MP3 to 5 MB
Fit an MP3 under 5 MB for messaging apps, forum uploads, and lightweight email attachments.
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Accepts .MP3, .WAV, .M4A, .AAC, .FLAC, .OGG, .OPUS · Up to 1,000 files
How it works
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Everything runs in your browser via WebAssembly. MP3 Compressor happens locally — no server involved.
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5 MB is the practical ceiling for an audio file you want to send instantly on a slow connection. At 128 kbps it holds about 5 minutes of music or roughly 15 minutes of spoken word — plenty for a voice memo, short interview clip, or a demo track. Below that, use Voice / Podcast mode to squeeze longer recordings down without noticeable quality loss on speech.
When you need 5 MB
- Slack file uploads on free plans
Slack free plans throttle uploads over ~5 MB in some regions. Pre-compressing keeps sends fast and reduces channel storage against your team's cap.
- Forum and BBS attachments
Reddit, phpBB, and Discourse instances commonly cap audio uploads at 5 MB. A single compressed MP3 fits inside a comment without hitting the limit.
- Voice memos on slow mobile data
5 MB uploads reliably on 3G in under 30 seconds. Ideal for sending a spoken note when Wi-Fi isn't available.
Frequently asked questions
It depends on the bitrate. At 128 kbps CBR (music-grade), 5 MB holds roughly 5 minutes. At 64 kbps mono (Voice / Podcast mode), it holds about 10 minutes. At 32 kbps (voice, low-quality), it stretches to 20+ minutes.
Turn on Voice / Podcast mode. It forces 64 kbps mono at 22.05 kHz — enough to hold a 20-minute spoken-word recording under 5 MB with no noticeable quality drop for speech. For music that long, you'll need to trim it first with the Audio Trimmer tool.
For voice: yes, essentially transparent. For music: 5-minute songs at 128 kbps sound fine on phone speakers and earbuds; audiophiles listening on studio monitors may notice softer treble. If quality matters, go with the 8 MB or 16 MB target instead.
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.
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.