Shrink MP3 file size by re-encoding at a lower bitrate. Batch compress multiple files and download as ZIP.
Free, runs in your browser.
Find SoundCloud channels that match your genre and book premieres or reposts - directly from Premierely.
Explore channelsAn MP3 compressor shrinks an MP3 file by re-encoding it at a lower bitrate, so it takes up less storage and uploads or attaches faster. This tool runs entirely in your browser using the Web Audio API and a local MP3 encoder - your files never touch a server, and you see the exact size reduction before you download anything.
It accepts .mp3 files and re-encodes them at 64, 96, 128 or 192 kbps.
Compressing an MP3 takes three steps:
Yes. Compression here means re-encoding at a lower bitrate, which removes more audio data than the original encode kept. The lower the bitrate, the smaller the file and the more noticeable the quality loss - especially on dense or bass-heavy tracks. Voice recordings and podcasts tolerate low bitrates much better than music does.
Pick based on what the file needs to sound like when you are done:
It depends on the starting bitrate. Compressing a 320 kbps MP3 down to 128 kbps cuts the file size by roughly 60%. Going from 320 kbps to 64 kbps saves closer to 80%. The exact percentage appears next to each file after conversion, so you can compare before downloading.
Drop in a batch of MP3s, pick one bitrate, and compress them all in parallel. When they finish, download the whole batch as a single ZIP with the size savings applied across every file.
If a file has already been compressed once, compressing it again stacks the quality loss - each re-encode throws away more data on top of what the last one removed. Compress from your best available source, and keep a copy of the original before you overwrite anything.
SoundCloud re-compresses every upload for streaming regardless of what you send, so there is little benefit to pre-compressing before uploading there - use your best source instead. This tool is more useful for email attachments, DMs, and any platform with a hard file size limit where a smaller MP3 gets the job done.
Looking to get your track on a SoundCloud channel? Premierely connects artists with channels for premieres and reposts.
Find channels on PremierelyDrop your MP3 onto the upload area, pick a lower bitrate than the original (128 kbps is a good default), then hit convert. You will see the exact size reduction next to each file before you download it.
128 kbps is a solid balance of size and quality for most tracks. Use 96 kbps for voice recordings or podcasts. Use 64 kbps only when file size matters more than fidelity - it is noticeably lower quality for music.
Yes. Re-encoding at a lower bitrate removes more audio data, which reduces quality. The lower the bitrate, the smaller the file and the more noticeable the quality drop, especially on complex or bass-heavy tracks.
It depends on the original bitrate. Compressing a 320 kbps MP3 down to 128 kbps typically cuts the file size by roughly 60%. The exact percentage shows next to each converted file.
No. Compression happens entirely in your browser using the Web Audio API and a local MP3 encoder. Your files never leave your device.
Yes. Add as many files as you want, convert them all in parallel, then download everything as a single ZIP.
Yes, this is a lossy re-encode - each pass loses more data than the last. Only compress from your best available source, and avoid compressing the same file more than once.
100 MB per file. There is no limit on the number of files you can compress.
Converting from a different format instead? The full audio converter handles WAV, M4A, FLAC, OGG, AAC and Opus to MP3 or WAV. Try the M4A to MP3 converter, FLAC to MP3 converter, or OGG to MP3 converter. Cut and trim with the MP3 cutter, or add smooth fades with the audio fade tool. Working from WAV? Use the WAV to MP3 converter. Every tool runs free in your browser with no upload.