Resources Hub » Knowledge base » How Do I Compress Audio Files to Email?

Most email providers have limits on the size of files their users can send in attachments. Plus, trying to attach large files is often just asking for trouble. So what do we do when we must email something like an audio file?

These files have to be compressed.

How do I compress audio files to email?

Compression reduces file sizes, which is very useful when trying to email large files such as .WAVs or .MP3 files. Read on to learn how it’s done.

How to compress audio files for email

Compressed audio files are usually between 128kbps and 320 kbps, or between a third and a tenth the size of the same file when it’s uncompressed. Smaller files mean the email sends faster.

There are two ways you can compress an audio file.

1. Zip them up in a folder.

Use this method when you’re mostly concerned about transmitting audio effortlessly, with a few clicks of a button.

To zip an audio file in Windows:

  1. Right-click on the file and select Send To.
  2. Choose Compressed (zipped) folder.
  3. Name your new zipped folder.

On a Mac:

  1. Select the file and either right-click or press CTRL while clicking.
  2. Select Compress “file name.”
  3. Name your newly compressed folder.

2. Use compression software.

Audio compression software is specially designed for compressing audio files. Such programs usually have more features to control sound quality and manipulate file types. For example, you can convert .WAV to the (usually smaller) .MP3 before compression. Some of our favorite free online tools include:

  • MP3Smaller, which is an online tool to compress .MP3 files.
  • AConvert is a browser-based audio converter and compressor that allows you to manage bitrates and sample rates.
  • Ogg Vorbis is an open-source compression software for audio that requires more control over bitrate variables. It also enables lossy compression for audio. (See below why that matters.)

How do you know which method to use?

How to measure the best method to compress audio files to email.

In audio, there are two types of compression: lossless and lossy.

Lossless compression does not remove data from the original file to compress it. The file that is decompressed is the same file that was initially compressed. Lossless compression occurs more commonly with text and spreadsheet files. This is because such content wouldn’t make sense if we started dropping words or cell values to make the file smaller.

On the other hand, lossy compression is more commonly used for video and sound. This compression reduces the file size by eliminating pieces of information. This dropped information, which may include pixels or parts of the sound wave, cannot be recovered. However, it usually doesn’t always affect the quality of the sound or image because these pieces are too small for us to notice.

Most free audio compression uses lossy compression, and that’s fine for the majority of situations, including those where you’ll find yourself emailing audio. Lossy compression reduces the audio size more than lossless compression.

Otherwise, if the file size doesn’t matter as much as quality, choose lossless; you can always convert it to lossy later.

Does it really matter?

You definitely should compress files before emailing them. This speeds up delivery and loading times. However, one of the most significant considerations when sending attachments in emails is whether or not your email is going to get caught in spam filters.

Finnish security firm F-Secure found that five common file types constitute 85 percent of malicious attachments: .ZIP, .DOC., .XLS, .PDF, and .7Z.

Both .ZIP and .7Z are the two most widely used compression types. Compression matters, but don’t send zipped files to strangers.

What now?

If you’re able to access an online audio compressor, it’s your best bet. Avoid .ZIP and .7Z if you’re sending this file to someone who doesn’t personally know you.  

Likewise, if you’re thinking of putting audio into an email campaign, it’s important to be super careful.


Check out our other tips to improve email deliverability.

This blog provides general information and discussion about email marketing and related subjects. The content provided in this blog ("Content”), should not be construed as and is not intended to constitute financial, legal or tax advice. You should seek the advice of professionals prior to acting upon any information contained in the Content. All Content is provided strictly “as is” and we make no warranty or representation of any kind regarding the Content.

Get started with Campaign Monitor today.

With our powerful yet easy-to-use tools, it's never been easier to make an impact with email marketing.

Try it for free