What quality should I expect from the AMR output?

Our converter preserves as much fidelity as AMR Audio allows. Where Sun AU Audio carries information that AMR Audio cannot represent, that information is mapped to the closest equivalent (for example, color spaces, codec parameters, or metadata fields). For most everyday uses the result is indistinguishable from the source.

Will my audio metadata (title, artist, album, cover art) be preserved?

Yes, where the target format supports it. AMR Audio can carry standard tag information (ID3, Vorbis comments, or the equivalent depending on the format), and we copy as much metadata as possible from your AU file. Cover art and embedded album artwork are preserved when both formats support it. Highly format-specific metadata that has no equivalent in AMR is dropped.

What file size should I expect for the AMR output?

The output size depends on the content and the compression characteristics of AMR Audio. In most cases the AMR file will be in the same ballpark as your AU input, with differences driven by how each format encodes data. There is no fixed ratio — the converter does not change quality settings unless you ask it to.

When should I convert AU to AMR instead of staying with AU?

Convert when the application, device, or workflow you are targeting prefers AMR Audio over Sun AU Audio. If your current AU file already opens and behaves correctly everywhere you need it to, there is no benefit to converting — keep the original. The most common reasons to switch are compatibility (a tool only accepts AMR), distribution (recipients expect AMR), or feature requirements specific to AMR Audio.

What is the maximum AU file size I can convert?

MegaConvert accepts AU files up to 100 MB on the free service, which is enough for the vast majority of real-world Sun AU Audio files. If you have a larger file (typical for high-resolution video or uncompressed audio), please contact us — we can sometimes accommodate larger uploads for legitimate use cases.

Is my AU file safe and private when I upload it?

Yes. Your AU file is uploaded over HTTPS, processed in an isolated job environment, and deleted from our servers within one hour. We do not read, index, store, or share the contents of your file. No account is required, so the upload is not associated with a personal identity. See our privacy policy for the full details.

Convert AU to AMR

Free online AU to AMR converter. No signup required.

Drag & drop your file here

or click to browse

Max file size: 100 MB

Why Convert AU to AMR?

Understand when and why this conversion makes sense for your workflow.

Converting Sun AU Audio to AMR Audio ensures your audio files work across the widest possible range of devices, players, and streaming platforms. Audio formats differ significantly in their compression algorithms, bitrate support, and metadata handling. Whether you're archiving a music collection, preparing tracks for a podcast, or optimizing audio for a mobile app, selecting the right output format is essential for balancing playback compatibility with sound fidelity.

Sun AU Audio has a known limitation: largely obsolete for general-purpose audio use. In contrast, AMR Audio offers a key advantage: extremely small file sizes optimized for voice content. While Sun AU Audio is commonly used for unix and solaris system audio and sound effects, AMR Audio is better suited for mobile phone voice recording and voice memos.

MegaConvert processes your AU file and delivers a properly encoded AMR output, preserving audio quality within the limits of the target format — free, instant, and private.

AU vs AMR: Format Comparison

Side-by-side comparison of the source and target formats.

Property	AU (Source)	AMR (Target)
Extension	.au	.amr
Full Name	Sun AU Audio	AMR Audio
Compression	Varies	Varies
File Size	Varies	Small
Best For	Unix and Solaris system audio and sound effects	Mobile phone voice recording and voice memos
Browser Support	Varies	Varies

How to Convert AU to AMR

Follow these simple steps to convert your file in seconds.

Upload your AU audio
Drop your .au audio file into the upload zone or browse to select it. Both short voice clips and full-length tracks work — typical Sun AU Audio files (under 100 MB) upload in seconds even on a slow connection. Album art and metadata in the file are read automatically.
Start the AMR encode
Press the convert button to start. The audio stream is decoded from Sun AU Audio into PCM, then re-encoded as AMR Audio at a quality preset that matches the source bitrate where possible. Sample rate, channel count, and bit depth are preserved unless the target format restricts them.
Wait for the audio to finish encoding
Encoding speed depends on the length of the audio and the codec. Short clips finish in a few seconds; full-length albums can take 30 seconds or so. We do not throttle conversions — the limit is just the encoder's natural speed on the underlying hardware.
Download your .amr file
When the conversion finishes, click the download link to save the new AMR Audio file to your computer. The file is yours — no watermarks, no expiration on the file itself, and no MegaConvert account is required to download it.

Tips for Converting AU to AMR

Practical advice to get the best results from this conversion.

Why this conversion is worth doing

Sun AU Audio has a known limitation: largely obsolete for general-purpose audio use. AMR Audio addresses this with a key advantage: extremely small file sizes optimized for voice content. Converting from AU to AMR is most worthwhile when this specific trade-off matters for the way you intend to use the file.

Match the format to the actual workflow

Sun AU Audio is most commonly used for unix and solaris system audio and sound effects, while AMR Audio is the standard for mobile phone voice recording and voice memos. If your workflow is closer to the second pattern, converting makes sense. If you are still working in a context where AU is the norm, converting may create unnecessary compatibility friction with collaborators or tools that expect the source format.

Watch for this limitation in the AMR output

AMR Audio has its own limitation worth understanding before you commit: very poor quality for music or non-speech audio. After the conversion completes, open the AMR file and verify that this limitation does not affect your specific use case — for some workflows it is irrelevant; for others it can be a deal-breaker.

Understand lossy vs. lossless before converting

Converting from a lossy format like MP3 to a lossless format like FLAC or WAV does not restore lost audio data — it only changes the container. If you need true lossless quality, always start from an uncompressed or lossless source. Converting lossless to lossy, however, is a valid way to reduce file size for streaming or mobile playback.

Understanding AU and AMR Formats

Learn about the source and target file formats to understand what happens during conversion.

Source Format

Sun AU Audio

audio/basic

AU is an audio file format introduced by Sun Microsystems and commonly associated with Unix and NeXT systems. It supports various encodings including uncompressed PCM, mu-law, and A-law compression, with a simple header structure. AU was one of the earliest audio formats supported on the web and remains used in Unix-based audio programming.

Advantages

Simple, well-documented format with a minimal header
Native support in Unix, Solaris, and Java audio APIs
Supports multiple encoding types including mu-law for telephony

Limitations

Largely obsolete for general-purpose audio use
Limited metadata support and no modern compression options
Poor support in consumer audio software and devices

Common Uses

Unix and Solaris system audio and sound effects
Java application audio playback (javax.sound)
Legacy telephony and voice processing systems

Target Format

AMR Audio

audio/amr

AMR (Adaptive Multi-Rate) is a compressed audio format optimized specifically for speech encoding, widely used in mobile telecommunications. It employs adaptive bitrate encoding that adjusts between 4.75 and 12.2 kbps based on network conditions, prioritizing speech intelligibility over music quality. AMR is the standard speech codec for GSM and UMTS mobile networks worldwide.

Advantages

Extremely small file sizes optimized for voice content
Adaptive bitrate adjusts to network conditions in real-time
Standard codec in GSM/3G mobile networks worldwide

Limitations

Very poor quality for music or non-speech audio
Limited to narrowband (8 kHz) or wideband (16 kHz) sampling
Not suitable for high-fidelity audio or media production

Common Uses

Mobile phone voice recording and voice memos
Cellular voice call encoding in GSM/3G networks
MMS voice message attachments

Frequently Asked Questions

Common questions about converting AU to AMR.

Related Conversions

Explore other conversions related to AU and AMR.

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AU to MP3 AU to WAV AU to FLAC AU to AAC AU to OGG AU to WMA AU to M4A AU to OPUS AU to AIFF AU to AC3

Other conversions to AMR

MP3 to AMR WAV to AMR FLAC to AMR AAC to AMR OGG to AMR WMA to AMR M4A to AMR OPUS to AMR AIFF to AMR AC3 to AMR

Convert AU to AMR

Why Convert AU to AMR?

AU vs AMR: Format Comparison

How to Convert AU to AMR

Upload your AU audio

Start the AMR encode

Wait for the audio to finish encoding

Download your .amr file

Tips for Converting AU to AMR

Why this conversion is worth doing

Match the format to the actual workflow

Watch for this limitation in the AMR output

Understand lossy vs. lossless before converting

Understanding AU and AMR Formats

Sun AU Audio

Advantages

Limitations

Common Uses

AMR Audio

Advantages

Limitations

Common Uses

Frequently Asked Questions

What quality should I expect from the AMR output?

Will my audio metadata (title, artist, album, cover art) be preserved?

What file size should I expect for the AMR output?

When should I convert AU to AMR instead of staying with AU?

What is the maximum AU file size I can convert?

Is my AU file safe and private when I upload it?

Related Conversions

Other conversions from AU

Other conversions to AMR