Free · No Upload · Instant

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

Convert M4A to AU online for free. Fast, private MPEG-4 Audio to Sun 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 M4A to AU

Upload your M4A file by clicking "Choose Files" or drag and drop it.

Select AU as the output format.

Click "Convert Now" and download your converted file.

About M4A Format

Extension: .m4a
Full name: MPEG-4 Audio

About AU Format

Extension: .au
Full name: Sun Audio

Frequently Asked Questions

Is it safe to convert M4A to AU 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 M4A to AU?

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 M4A to AU 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 M4A file, and download the converted AU file.

Will I lose quality converting M4A to AU?

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 M4A files to AU?

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

What is the difference between M4A and AU?

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

Why Convert M4A to AU?

Advantages

✓Sun 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

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

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