Compress Audio to a Target Size
Tell it the size you need and it works out the bitrate, reducing channels or sample rate only when it has to.
MP3, WAV, M4A, FLAC, OGG, Opus, AIFF, WMA, AMR and the sound of most videos. Files stay on your device.
How it works
- Choose your audio file.
- Enter the size you need in MB, or pick a preset such as WhatsApp or email.
- Click Compress; if the first try is over the limit, the tool retries with measured sizes.
- Check the before and after numbers, then download.
How the size is hit
Enter the size in megabytes (1 MB is 1,000,000 bytes). The tool subtracts what the file container needs, works out the bitrate that fits the duration, encodes, and measures the real result. If the file ended too big or too far under, it corrects the bitrate from what it measured and tries again, at most twice more. A file that fits usually ends up between 85 and 100 percent of the target, and never over it.
MP3 can only use fixed bitrate steps (96, 112, 128, 160 kbps and so on), so a result can land a little further under the target than with AAC, Opus or Vorbis, which can be tuned finely.
When the size is tight
A long recording at a small size needs a very low bitrate. Before it lets quality fall too far, the tool mixes down to mono, then lowers the sample rate, and it tells you each time it did. If even the lowest settings of the format cannot reach the size, you get a clear message with what it would take, and nothing is downloaded. Trim the audio or pick a larger size.
The presets for email, WhatsApp and Discord are common limits only. Services change them, and they differ by plan, so check the one you use and leave some room.
Lossless sources
WAV and FLAC files cannot be squeezed to an exact size without losing detail, so a size target converts them to a lossy format: MP3 by default, or M4A, Opus or OGG if you choose. For a smaller lossless file, use the other tools on this page: FLAC, a lower bit depth, mono or a lower sample rate.
Questions
Is the result guaranteed to be under my size?
Yes, or the tool says it could not do it. It measures the real encoded file and only hands you one that fits, or explains why none can.
Why is the file smaller than the size I asked for?
The tool aims for about 97 percent of your target to leave room for tags and rate-control differences, and a file that is already smaller than the target is kept at its own bitrate rather than inflated. MP3 also moves in fixed steps.
What size should I choose for WhatsApp, email or Discord?
The presets use common limits (10 MB for email and Discord, 16 MB for WhatsApp), but limits change and depend on your plan. Check the service, and choose a size a little below its limit.
Can it compress a whole batch to the same size?
Yes. Each file is compressed to the size you set, separately. With Maximum size, files that are already under it are left untouched.
Is my audio uploaded?
No. Compression runs in your browser on your device. The only downloads are the page itself and, the first time you use a format, a small encoder file from this site.