Compress Audio in iTunes: How to Do It

Updated 6 November 2026 · Standard formula, shown below

To compress audio in iTunes, you change the import settings to a compressed format like AAC or MP3, then convert the selected songs. This reduces file size while keeping the audio playable in Apple’s ecosystem and most other players.

Background: Why Compress Audio at All

Audio files come in two broad types: uncompressed (like WAV or AIFF) and compressed (like AAC, MP3, or FLAC). Uncompressed files preserve every bit of the original recording, making them large—a typical 3-minute song in WAV is about 30 MB. Compressed formats discard some audio data that most ears can’t perceive, shrinking that same song to roughly 3–5 MB at a standard bitrate. That difference matters when you’re storing thousands of songs on a phone, tablet, or laptop with limited storage.

iTunes (and the modern Music app on macOS) has always offered a built-in way to convert files to compressed formats. The feature is part of the app’s import settings, originally designed for ripping CDs but equally useful for shrinking existing files. The compression is lossy—some data is removed—so the trade-off is file size versus audio fidelity. For most listening on earbuds or car speakers, the difference is negligible.

How iTunes Compression Works

When you compress a file in iTunes, the app decodes the original audio and re-encodes it using the format and bitrate you selected. The process is called transcoding. It does not simply remove data from the existing file; it creates a brand-new file in the new format. The original file remains untouched unless you delete it manually.

The key settings are found in Preferences > General > Import Settings (on Mac) or Edit > Preferences > General > Import Settings (on Windows). There you choose the Import Using dropdown and the Setting dropdown. The default is usually AAC at 128 kbps, which is a good balance for most users. You can also choose MP3, AIFF, or Apple Lossless, though the latter two are not compressed in the same lossy way—AIFF is uncompressed, and Apple Lossless is lossless (smaller than WAV but still larger than AAC).

How to Compress Audio in iTunes (Step-by-Step)

Open iTunes (or the Music app on macOS Catalina and later).
Go to Preferences (Mac: iTunes > Preferences; Windows: Edit > Preferences).
Click the General tab, then click the Import Settings button.
In the Import Using dropdown, select AAC Encoder or MP3 Encoder.
In the Setting dropdown, choose a bitrate. For AAC, 128 kbps is standard; for MP3, 128 kbps or 192 kbps are common.
Click OK to save the settings.
Select the songs you want to compress in your library (hold Cmd/Ctrl to select multiple).
Right-click (or Control-click) the selection and choose Create AAC Version (or Create MP3 Version, depending on what you selected).
A new file appears next to the original with the same name. The original remains.
If you want to remove the original to save space, right-click the original and select Delete, then choose Move to Trash (or Recycle Bin). Be sure you have a backup if you delete the original.

Choosing the Right Format and Bitrate

The two main compressed formats in iTunes are AAC and MP3. AAC (Advanced Audio Coding) is the default and generally offers better quality at the same bitrate as MP3. It is also the native format for Apple Music and iTunes Store downloads. MP3 is more universally compatible—it works on virtually every device, including older car stereos and gaming consoles. If you plan to play the files on a non-Apple device, MP3 might be safer.

Bitrate determines how much data is retained per second of audio. Common choices:

128 kbps – good for spoken word or casual listening; small files.
192 kbps – a good balance for music on most devices.
256 kbps – higher quality, larger files; a good choice for audiophiles on a budget.
320 kbps – the highest MP3 bitrate; near-CD quality but files are larger.

For most people, 128 kbps AAC is indistinguishable from the original on typical earbuds. If you have high-end headphones or a quiet listening environment, choose 192 or 256 kbps. Remember, you can always re-encode later, but you can’t recover the lost data from a low-bitrate file.

Common Problems and Misconceptions

One frequent issue: the Create AAC Version option is grayed out. This happens when the selected file is already in AAC format. iTunes won’t compress an AAC file to another AAC file by default. You can force it by changing the import format to MP3, then creating an MP3 version, but that’s a double lossy conversion. Better to keep the original or use a different tool.

Another misconception is that compressing a lossy file (like MP3) to another lossy format (like AAC) will improve quality. It won’t—it will degrade it slightly. Always compress from the highest-quality source you have, ideally a WAV, AIFF, or Apple Lossless file. If you only have a 128 kbps MP3, converting it to 256 kbps AAC won’t add quality; it will just make a larger file with the same underlying audio data.

Also, note that iTunes compression does not support batch conversion of entire folders at once. You must select the songs manually or use a playlist. If you have a large library, consider using a dedicated audio converter tool that can process folders in bulk.

Alternatives to iTunes Compression

If you need more control or batch processing, third-party tools like XLD (for Mac) or Foobar2000 (for Windows) offer extensive options. These are free, open-source, and can convert between many formats with precise bitrate and quality settings. They also support lossless compression like FLAC, which iTunes does not natively support (though you can convert FLAC to ALAC for iTunes).

Another alternative is to use the command line with FFmpeg, a powerful tool that can transcode any audio file. It’s not for beginners, but it’s the most flexible. For most users, though, iTunes’ built-in converter is sufficient and requires no extra software.

Frequently Asked Questions

Does compressing audio in iTunes reduce quality?

Yes, lossy compression reduces quality, but the degree depends on the bitrate. At 128 kbps AAC, most listeners cannot hear a difference on standard speakers or earbuds. At 64 kbps, you’ll likely notice artifacts. The key is to choose a bitrate high enough for your listening environment.

Can I compress audio without losing quality?

You can use a lossless format like Apple Lossless (ALAC) or FLAC, which compresses the file without discarding any audio data. However, the file size reduction is modest—roughly 40–50% compared to WAV. For true lossless compression, you need to start from an uncompressed source.

Why is my compressed file larger than the original?

This happens when you convert a low-bitrate file (like 96 kbps MP3) to a higher bitrate (like 256 kbps AAC). The encoder adds padding, but the audio quality is still limited by the original. Always compress from a higher-quality source to avoid this.

How do I compress a whole album at once?

Select all songs in the album (click the first, hold Shift, click the last), then right-click and choose Create AAC Version. All selected songs will be converted in one go. The original files remain.

Will compressed files work on Android or other devices?

Yes, AAC and MP3 are universally supported. You can copy the files from your iTunes library folder to any device. On Windows, the files are in Music\iTunes\iTunes Media\Music; on Mac, in ~/Music/iTunes/iTunes Media/Music.

Can I compress audio in the Apple Music app?

Yes, the steps are the same. In the Music app on macOS, go to Settings > General > Import Settings, then right-click a song and choose Create AAC Version. The interface is nearly identical to iTunes.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.