Free · No Upload · Instant

Convert AU to M4A Free Online — Best AU to M4A Converter 2025

Convert AU to M4A online for free. Fast, private Sun Audio to MPEG-4 Audio converter — no upload, no signup. Works in your browser instantly.

Choose Files

or drag and drop files here

Max file size: 2GB

Your files are processed locally in your browser. Nothing is uploaded to any server.

How to Convert AU to M4A

Upload your AU file by clicking "Choose Files" or drag and drop it.

Select M4A as the output format.

Click "Convert Now" and download your converted file.

About AU Format

Extension: .au
Full name: Sun Audio

About M4A Format

Extension: .m4a
Full name: MPEG-4 Audio

Frequently Asked Questions

Is it safe to convert AU to M4A online?

Yes! Convert999 processes all files directly in your browser. Your files are never uploaded to any server, ensuring complete privacy and security.

How long does it take to convert AU to M4A?

Conversion is nearly instant for most files. Large files may take a few seconds depending on your device's processing power.

Is there a file size limit?

Convert999 supports files up to 2GB. Processing happens locally, so larger files depend on your device's available memory.

Do I need to install any software?

No installation required. Convert999 works entirely in your web browser on any device.

Can I convert AU to M4A on my phone?

Yes! Convert999 works on any device with a web browser — iPhone, Android, iPad, or desktop. No app installation required. Simply open the converter, upload your AU file, and download the converted M4A file.

Will I lose quality converting AU to M4A?

Convert999 uses high-quality conversion algorithms to minimize quality loss. For lossless formats, the conversion is exact. For lossy formats like images and audio, we use optimized settings that balance quality and file size.

Can I batch convert multiple AU files to M4A?

Yes, Convert999 supports batch conversion. Select or drag & drop multiple AU files and convert them all to M4A format at once. Each file is processed locally in your browser.

What is the difference between AU and M4A?

Sun Audio (AU) and MPEG-4 Audio (M4A) differ in compression, compatibility, and features. AU is optimized for its native use cases, while M4A may offer different advantages. Visit our AU vs M4A comparison page for a detailed breakdown.

Why Convert AU to M4A?

Advantages

✓MPEG-4 Audio offers better compatibility with modern applications and workflows
✓Converting is completely free with no file size limits on Convert999
✓Your files never leave your device — 100% private and secure conversion
✓Instant conversion without waiting for server processing

Key Differences

→AU (Sun Audio) is optimized for its native use cases
→M4A (MPEG-4 Audio) may offer different compression or feature set
→Choose based on your target platform, quality needs, and file size requirements

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AUMP3 AUWAV AUFLAC AUAAC AUOGG AUWMA MP3M4A WAVM4A FLACM4A AACM4A OGGM4A WMAM4A

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