Guide · Audio
Compress audio files offline
To make audio files smaller without uploading them, add them to Crunchy (or drop a whole music or recordings folder), keep the format or pick MP3, AAC or Opus, and press Crunch. Crunchy compresses each file on your own PC and saves a smaller copy in a Crunchy folder in your Downloads folder; the original stays as it was.
01 / What Crunchy does
Smaller audio, without the guesswork.
Crunchy compresses audio with FFmpeg at the level you pick (Light, Balanced or Maximum) and never re-encodes a file just to save a few bytes.
Lossless on Light
WAV, AIFF, APE and WavPack become FLAC at its strongest setting, and FLAC files are recompressed the same way. Every sample stays bit for bit identical, 24-bit and high sample rates included.
Same type, MP3, AAC or Opus
Same type keeps each file's format (WAV and FLAC become AAC on Balanced and Maximum). MP3 plays on everything, AAC (.m4a) on phones, Windows, Macs and browsers, and Opus makes the smallest files.
Sensible bitrates
Balanced: AAC 192 kb/s, Opus 128 kb/s, MP3 LAME V4. Maximum: AAC 128 kb/s, Opus 96 kb/s, MP3 V6. Mono files get about 60% of that.
No needless re-encoding
An MP3, AAC, Ogg or Opus file is only re-encoded when its bitrate is at least 1.4 times the level's target. Re-encoding at a similar bitrate only costs quality, so smaller files are kept, apart from tidying their tags and cover art.
Tags and cover art kept
Title, artist, album, track, date, genre and lyrics stay; the cover becomes a JPEG of at most 600 px on Balanced and Maximum. Strip metadata removes the rest, such as comments and the encoder name.
Channels kept
Stereo stays stereo unless you switch on Allow mono: then stereo files whose two channels are identical are saved as mono (about 40% smaller). Surround is never downmixed, and audio above 48 kHz is resampled to 48 kHz for lossy formats. A file that doesn't get smaller is kept and marked Already optimized.
Supported audio formats
- MP3
.mp3 - AAC
.m4a .aac - WAV
.wav - FLAC
.flac - Ogg Vorbis
.ogg .oga - Opus
.opus - WMA
.wma - AIFF
.aiff .aif .aifc - APE
.ape - WavPack
.wv - AMR
.amr - MKA
.mka
A few audio files are encoded at a time, while documents, images and videos in the same batch keep compressing alongside.
02 / Pick your settings
Which settings to use for audio.
- Light with Same type to archive recordings and music losslessly: WAV becomes FLAC and nothing is lost.
- Balanced for a music library you want to keep listening to, in a fraction of the space.
- Maximum with Opus for podcasts, lectures and voice notes, where size matters most.
- MP3 when the files have to play on an old car stereo or MP3 player.
The Audio page starts from your Settings defaults and remembers custom compression choices across batches and app restarts. Reset to default returns to your latest Settings defaults. Audio always saves as separate files, never a ZIP.
Need it under a size limit?
Switch on Target size and type the limit. For audio, Crunchy works out the bitrate that fits from the length of the recording, in at most three passes. Below a quality floor (Opus 24 kb/s, AAC 48 kb/s, MP3 64 kb/s in stereo) it switches to 32 kHz, and to mono only when Allow mono is on; if stereo can't reach the goal, the smallest stereo result is kept and marked over target.
Then open the before/after compare: for audio it shows the spectrum of both files, so you can see which high frequencies an encoder left out.
03 / How to
Compress audio in three steps.
Add the files
Drag audio files or a folder onto Crunchy, or right-click in Explorer and choose Compress with Crunchy. Audio files always land on the Audio page, even when you drop them with other files. Watch folders pick up new recordings by themselves.
Choose how small
Keep Same type or pick MP3, AAC or Opus, choose a level, and switch on Target size if the files have to fit a limit.
Crunch
Press Crunch. Each row shows the format and bitrate before and after, for example AAC 192 kb/s · stereo.
crunchy -l light "C:\Users\me\Music\Recordings"crunchy -a opus -l maximum "C:\Users\me\Music\Podcasts"-a takes same, mp3, aac or opus. crunchy --deps shows the installed FFmpeg and whether an update is available.
Powered by FFmpeg. Audio compression uses FFmpeg, the same free, open-source toolkit as video compression, so there is nothing extra to install: once the video and audio tools are there, both work. About the tools.
FAQ
Common questions.
More answers in the main FAQ.
Will Crunchy make my music sound worse?
Not on Light: Crunchy only compresses losslessly there, turning WAV into FLAC with every sample kept bit for bit, and it never re-encodes MP3 or AAC files. On Balanced and Maximum, lossless files become AAC at 192 or 128 kb/s (or the MP3 or Opus you pick). Files that are already lossy are only re-encoded when their bitrate is well above the level's target, because re-encoding at a similar bitrate only adds loss.
Which audio format should I pick in Crunchy?
Same type is a good default: each file keeps its format, and WAV or FLAC becomes FLAC on Light or AAC (.m4a) otherwise. Pick MP3 when the files must play on very old players, AAC for phones, Windows, Macs and browsers, and Opus for the smallest files at the same quality; some older devices can't play Opus.
Does Crunchy keep tags, album art and the sample rate?
Yes. Crunchy keeps the title, artist, album, track number, date, genre and lyrics, and the cover art; on Balanced and Maximum the cover is saved as a JPEG of at most 600 px. With Strip metadata on, other tags such as comments and the encoder name are removed. Lossless FLAC keeps the sample rate and 24-bit depth, while lossy formats are resampled to 48 kHz when the source is above that. Stereo stays stereo unless you switch on Allow mono, which saves stereo files whose two channels are identical as mono.
Ready to crunch?
Free for Windows 10 & 11. No uploads, no account, no size limits.