MP3 Compressor: Reduce MP3 File Size Online

Compress MP3 files in your browser. Pick a bitrate, set a size limit such as 16 MB for WhatsApp, or remove cover art. Add several files at once. Nothing is uploaded.

Rate MP3 Compressor: Reduce MP3 File Size Online

How useful was this tool? Your rating helps others find it.

Three ways to reduce MP3 file size

Choose the method that fits what you need. The expected size of every file appears before you start.

  • Pick quality. Encode the audio again at a bitrate you choose, from 32 to 256 kbps. Good when you know the quality you want.
  • Target size. Enter a limit such as 16 MB. The tool picks the highest bitrate that stays under it, file by file.
  • No re-encoding. Remove the cover art and tags and copy the audio as it is. The file gets smaller and the sound does not change.

Best bitrate for compressing MP3 files

The table shows how much space one minute of audio takes at each setting. Multiply it by the length of your track to get the file size.

BitrateGood forPer minuteOne hour
32 kbpsVoice memos, speech only0.24 MB14.4 MB
64 kbpsPodcasts and audiobooks0.48 MB28.8 MB
96 kbpsClear speech, light music0.72 MB43.2 MB
128 kbpsMusic, standard quality0.96 MB57.6 MB
192 kbpsMusic, high quality1.44 MB86.4 MB
256 kbpsClose to the original1.92 MB115.2 MB

These are constant bitrates. They give a size you can predict, which is what a size limit needs.

Compress MP3 for WhatsApp and email (16 MB and 25 MB)

WhatsApp accepts audio up to 16 MB when you send it as media. Gmail allows attachments up to 25 MB. The table shows how many minutes of audio fit under each limit.

BitrateWhatsApp, 16 MBGmail, 25 MB
32 kbps66 min104 min
64 kbps33 min52 min
96 kbps22 min34 min
128 kbps16 min26 min
192 kbps11 min17 min
256 kbps8 min13 min

Use the Target size method: enter the limit and the tool picks the highest bitrate that fits. A file that is already under the limit stays untouched. WhatsApp also lets you send a larger file as a document, up to 2 GB, without compressing it.

Does compressing an MP3 reduce quality?

Yes, when the tool encodes the audio again, because MP3 is a lossy format. Each pass loses a little detail, mostly in the high frequencies. At 128 kbps most people hear no difference on speakers. At 64 kbps and below, music starts to sound thin, while speech stays clear. Removing cover art and tags is the exception: it does not touch the audio.

  • Pick a bitrate lower than the one shown for your file. Encoding a 128 kbps file at 128 kbps again makes it no smaller and loses detail.
  • Keep the original and compress a copy. A compressed file cannot get its detail back.
  • For speech, mono sounds cleaner than stereo at low bitrates. The mono option is made for this.
  • Use the Listen button on each result to compare it with the original before you download it.

How this MP3 compressor works

This compressor encodes your MP3 again at a lower bitrate. The bitrate is the amount of audio data stored for each second, so a lower value means a smaller file. The tool reads the length and bitrate of each file first, which lets it show the expected size before you press Compress.

The encoding runs in your browser. FFmpeg, compiled to WebAssembly, decodes the file and writes a new MP3 with the LAME encoder. Your audio is never sent to a server. On first use the browser downloads the engine, about 32 MB, and keeps it for later visits.

You can set a bitrate yourself, or enter a size limit such as 16 MB and let the tool choose the highest bitrate that fits. A third method removes only the cover art and tags and copies the audio without encoding it again. That is the one way to shrink an MP3 with no change in sound.

How to compress an MP3 file in 3 steps

1

Add your MP3 files

Drop up to 25 files into the box or choose them from your device. The tool shows the length, bitrate and size of each file.

2

Choose a bitrate or a size limit

Pick a bitrate, enter a size limit such as 16 MB, or remove only the cover art and tags. The expected size appears before you start.

3

Compress and download the MP3

Select Compress. Listen to the result if you like, then download each file or all of them as one ZIP.

Example Usage

Setting 64 kbps and mono cuts a 97.9 MB episode to about 32.6 MB, which is 67% smaller. Speech stays clear.

Input
podcast-episode.mp3 192 kbps, stereo, 68 min, 97.9 MB
Output
podcast-episode-compressed.mp3 64 kbps, mono, 68 min, 32.6 MB

Frequently Asked Questions

How do I compress an MP3 file?
Add your file, choose a bitrate or a target size, and select Compress. When it finishes, download the new file. The work happens in your browser, so the file never leaves your device.
Can I compress an MP3 without losing quality?
Not by re-encoding it. MP3 is a lossy format, so every new encode removes a little more detail. One change costs nothing: removing the cover art and tags. The No re-encoding method does that and copies the audio exactly as it is. Cover art often takes several hundred KB or more, so the saving can be noticeable.
How do I compress an MP3 for WhatsApp?
WhatsApp limits audio sent as media to 16 MB. Open Target size, choose 16 MB and add your files. The tool picks the highest bitrate that stays under the limit and leaves files that already fit as they are. If you would rather not compress, send the file as a document. WhatsApp allows documents up to 2 GB.
How do I get an MP3 under 10 MB or 5 MB?
Open Target size and type the limit, or use one of the buttons. The tool works out the bitrate from the length of each file and shows the expected size before you start. If a file is too long to reach the limit even at 32 kbps, the tool says so and shows the smallest size it can reach.
Which bitrate should I use for a podcast or audiobook?
64 kbps in mono keeps speech clear and uses about 0.48 MB per minute, so a one-hour episode takes about 28.8 MB. For speech with light music, use 96 kbps. For music, use 128 kbps or 192 kbps.
Why did my MP3 not get smaller?
The bitrate you chose was not lower than the bitrate of the file. A 128 kbps file encoded at 128 kbps stays about the same size and loses quality. The tool shows the bitrate of each file and warns you when a setting will not make it smaller. Pick a lower bitrate or set a target size.
Is my MP3 uploaded to a server?
No. Compression runs in your browser tab with FFmpeg compiled to WebAssembly. The only download is the audio engine, about 32 MB on first use. Your browser keeps it for the next visit.
Can I compress several MP3 files at once?
Yes. Add up to 25 files. They compress one after another with the same settings. Download them one by one, or all together as a ZIP file.
Are the title, artist and cover art kept?
Yes, by default. You can remove the cover art, the tags, or both in the options.
How long does compression take?
A typical song takes a few seconds. A one-hour podcast takes about a minute on a recent laptop. Phones and older computers take longer. A progress bar shows how far each file has come.
Is there a file size limit?
Each file can be up to 250 MB. The browser holds the file in memory while it works, so very large files can fail on phones and older computers. If a large file fails, try a computer with more memory.
Can I compress WAV, M4A or FLAC files?
This tool accepts MP3 files only. For WAV files, use the WAV Compressor. To turn M4A, FLAC and other audio formats into MP3, use the matching converter, then compress the result here.

Related Tools

Try It

WAV to MP3 Converter

Convert WAV files to MP3 format instantly. Compress large audio files for easier sharing and streaming.

Try It

MP4 to MP3 Converter

Extract audio from MP4 videos and save as MP3 files with selectable bitrate.

Try It

M4A to MP3 Converter

Convert Apple M4A audio files to universally compatible MP3 with bitrate control.

Try It

MP4 Compressor

Compress MP4 videos online. Reduce file size while maintaining quality options.

Try It

FLAC to MP3 Converter

Convert FLAC lossless audio files to compact MP3 format with selectable bitrate in your browser.

Try It

WAV Compressor

Compress WAV audio files with preset quality levels in your browser and download smaller files.

The MP3 Compressor: Reduce MP3 File Size Online is maintained by CodeItBro. We aim to provide the best free developer tools on the web. If you have feedback or suggestions, please visit our contact page.

As featured on

CodeItBro - Free dev tools + practical guides to help you ship faster | Product HuntCodeItBro - Free Online Developer Tools badgeCodeItBro badge