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MP3 compressor

Reduce an MP3’s file size by lowering its bitrate, or make it small enough to fit a size in MB. It stays an MP3, it’s free, and it’s never uploaded.

Files stay on your device

Drop an MP3 to compress it

Make an MP3 smaller at a lower bitrate, or small enough to fit a size in MB. It stays an MP3.

MP3, M4A, WAV, FLAC, and other audio, or a video with sound.

How to compress an MP3

Open the MP3 and choose Balanced (96 kb/s) or Smallest (64 kb/s), or choose Size in MB and type the limit it has to fit. Each choice shows about how big the new MP3 will be before you save it. The MP3 compressor works in your browser on Windows, Mac, Android, or iPhone, and it also turns a WAV, M4A, or video’s sound into a small MP3.

  1. Step 1

    Choose the MP3
    Pick it from your phone or computer.

  2. Step 2

    Lower the bitrate
    96 or 64 kb/s, or a size in MB for it to fit.

  3. Step 3

    Download the MP3
    A smaller MP3 that plays everywhere.

What to expect

Supported inputs
MP3 files, and any other audio or video this browser’s engine can read.
What happens
The MP3 is encoded again at the bitrate you choose, from 128 down to 32 kb/s. Other audio, and a video’s sound, is saved as an MP3.
Limits
Only bitrates below the MP3’s own are offered, since a higher one would make it bigger. At 32 kb/s, the lowest, an hour is about 14 MB.

Private by design

Your video stays on your device

Mastershot processes your file locally in this browser. It does not need to be uploaded to a server, and you do not need an account to use the tool.

  • No upload
  • No signup
  • No watermark

Questions

Lower its bitrate. Choose Balanced or Smallest and select Compress, or choose Size in MB and type the limit. A 4-minute song at 320 kb/s is 9.6 MB, and about 2.9 MB at 96 kb/s.

96 kb/s for music you’ll still listen to, and 64 kb/s or lower for speech, such as a podcast, lecture, or voice note. 128 kb/s keeps the most detail.

Yes. Choose Size in MB, type 5, and it gets the best bitrate that fits. If even 32 kb/s is too big, it tells you the smallest size it can reach, so you can cut the MP3 shorter first.

Yes. There’s no sign-up, no watermark, and no limit on how long the MP3 is, and it’s never uploaded.

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