Free tool
Audio compressor
This audio compressor makes a recording smaller so you can send it: pick a quality, or type the size it has to fit, and it shows the file’s size now and after before you start. Any audio file, or a video’s sound, goes in; a small MP3 comes out.
- Free
- Size shown before and after
- Nothing is uploaded
Drop your audio file here, or Choose your audio file
MP3, M4A, WAV, FLAC, OGG, AAC, or the sound of an MP4, MOV or WebM video, up to 1 GB and 2 hours. Everything happens in your browser; nothing is uploaded.
MP3 encoding by LAME, open-source software.
Compressing a meeting recording to email it? NoteOwl writes a summary with action items from the meeting on your Mac, and a page of notes is far smaller than any audio.
How it works
How do you compress an audio file?
Add the file. Under Choose by, pick a quality and see each one’s size beside it, or switch to Target size and type the megabytes it must fit in. The line below shows the size now and after. Press Compress audio, then download the MP3.
- 1
Add the recording
A WAV from a recorder, an M4A voice memo, a FLAC, or an MP4 whose sound you want to send.
- 2
Pick a size
Choose a setting by quality, or let the compressor choose the best one that fits in the megabytes you type.
- 3
Compress and send
The MP3 downloads with “-compressed” added to its name, ready to attach or upload.
How much smaller can an audio file get?
Usually many times smaller. WAV recordings shrink the most: a 74 MB meeting WAV came out at 2.3 MB, 97% smaller, at the speech setting Small. A file that is already an MP3 or M4A has less to give.
- Smallest
- Bitrate32 kbps mono
- An hour takesAbout 14 MB
- Small
- Bitrate48 kbps mono
- An hour takesAbout 21 MB
- Medium
- Bitrate64 kbps mono
- An hour takesAbout 27 MB
- Good
- Bitrate96 kbps, stereo kept
- An hour takesAbout 41 MB
- High
- Bitrate128 kbps, stereo kept
- An hour takesAbout 55 MB
| Setting | Bitrate | An hour takes |
|---|---|---|
| Smallest | 32 kbps mono | About 14 MB |
| Small | 48 kbps mono | About 21 MB |
| Medium | 64 kbps mono | About 27 MB |
| Good | 96 kbps, stereo kept | About 41 MB |
| High | 128 kbps, stereo kept | About 55 MB |
How do you get a recording under 25 MB to email it?
Choose Target size and type 25, the attachment limit in Gmail. The compressor picks the highest bitrate that still fits, leaving a little room to spare, and shows the result before you start. At Small, 48 kbps, an hour of speech takes about 21 MB, so it fits.
If even the smallest setting won’t fit, the page says so and shows the smallest size it can reach; then split the recording with the audio splitter and send it in parts. A 6.2 MB podcast asked to fit in 2 MB came out at 1.93 MB, at 40 kbps.
Which setting is right for speech, and which for music?
Speech stays clear far lower than music does. The three mono settings, 32 to 64 kbps, suit calls, lectures, interviews and voice memos: one channel, so every bit goes to the voices. Keep Good or High for music, where stereo and the high notes matter.
A call or meeting
Small, 48 kbps mono: voices stay easy to follow at about 21 MB an hour.
A lecture to keep
Medium, 64 kbps mono, for a little more detail in a big room.
A song or a mix
Good or High, which keep both channels and the cymbals.
Is this the same as a compressor in music production?
No. In a studio, a compressor narrows the dynamic range, the gap between loud and quiet sounds, and leaves the file’s size alone. This one reduces the size in megabytes. For a recording that’s hard to hear, the volume booster raises its level without clipping.
Do you need to send the whole recording?
Often the notes are what people need. NoteOwl writes a summary with action items from a meeting on your Mac and exports it as a PDF, Markdown or text: a page or two that anyone can read in a minute, instead of an hour of audio.
FAQ
Questions about compressing audio
Is my recording uploaded to compress it?
No. The compressing happens in your browser: the page decodes the file, encodes the smaller MP3 and gives it back to you, all on your device. We watched the network while compressing a 74 MB WAV and the page sent nothing.
How accurate is the size shown before compressing?
Close: the MP3 is written at a constant bitrate, so its size follows from its length. For a 6:44 recording at 48 kbps the page showed about 2.3 MB beforehand, and the file came out at 2.31 MB.
Does compressing audio reduce its quality?
Some, because it keeps less detail; that is how the file gets smaller. The mono speech settings keep voices clear, and Good and High keep stereo and more of the high notes for music. Keep the original if you may need it later.
Can I compress the sound of a video?
Yes. Drop an MP4, MOV or WebM and the compressor saves its sound as a small MP3, leaving the picture out. A 45-second screen recording gave a 0.34 MB MP3 at 64 kbps.
What is the largest file it can compress?
Up to 1 GB and 2 hours of sound. A 74 MB WAV of almost seven minutes took between 2 and 5 seconds to compress, depending on the browser; the time grows with the length of the recording.
Why MP3 and not another format?
Because an MP3 opens everywhere: on every phone, in every email client and in upload forms that accept only a few formats. To keep every detail of a WAV instead, the WAV compressor makes a lossless FLAC.
Keep exploring
More audio editing tools
- MP3 compressorShrink an MP3 by re-encoding it at a lower bitrate in your browser, with the size before and after; only settings that make it smaller are offered
- WAV compressorMake a WAV smaller in your browser: lossless FLAC, a smaller WAV (lower sample rate, mono, 16-bit) or MP3, with the size before and after
- Volume boosterMake an audio file louder in your browser, up to +30 dB, with a limiter that stops it clipping and a preview before you save
- Audio speed changerSpeed up or slow down an audio file from 0.5× to 2× in your browser, keeping the pitch or not, and save it as MP3 or WAV
Related
- WAV to MP3 converterConvert WAV to MP3 in your browser, 16-bit to 32-bit float at any sample rate, and see how much smaller the MP3 is; nothing is uploaded
- MP4 to MP3 converterTurn an MP4 video’s sound into an MP3 in your browser, Zoom and Teams recordings included; nothing is uploaded
- Offline AI meeting notesEvery NoteOwl feature works offline after a one-time model download; what the app sends over the network, and what it never does
Send the notes, not the hour of audio
Free to download. Runs entirely on your Mac.
macOS 26 or later · Apple Silicon (M1 or newer) · 16 GB memory minimum, 24 GB recommended
About NoteOwl
NoteOwl is private AI meeting notes and memory for the Mac. It captures meetings without a bot joining the call, labels every speaker, writes summaries and action items, and builds a memory of every conversation that you can chat with — fully offline, because the speech recognition and the AI run on the Mac itself. Dictation into any app is free; Pro is a one-time purchase.
NoteOwl pricing: what’s free and what Pro adds
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