WAV to AU Converter

How to Convert WAV to AU Online

1. Upload Your WAV File: Drag and drop or click "+ Add Files" to select one or more .wav files from your computer. Batch conversion is supported — every file gets the same output settings.
2. Pick Audio Channel and Sample Rate: Leave Audio Channel on "Original" to preserve mono/stereo, or downmix stereo to mono for a smaller AU file. Set Audio Sample Rate to "Original" to keep the WAV's rate, or pick a target like 44100 Hz (CD-quality), 48000 Hz (DAT/DVD), 24000 Hz, 16000 Hz, or 8000 Hz (classic Sun μ-law telephony).
3. Trim the Audio (Optional): Use the Trim controls to set a start time and duration in HH:MM:SS.mmm or plain seconds — useful for clipping a single voice prompt out of a longer recording before exporting to AU.
4. Convert and Download: Click "Convert." The job runs on our servers and your AU file is ready to download in seconds — no sign-up, no watermark, no waiting on a desktop install.

Why Convert WAV to AU?

WAV (Waveform Audio File Format) is the Microsoft/IBM RIFF container released in 1991, almost always carrying uncompressed PCM and capped at roughly 4 GiB by its 32-bit size field. AU is the simple audio container introduced by Sun Microsystems for Unix workstations and NeXT systems; the headerless original was 8-bit μ-law data at 8000 Hz, and the format later grew to carry 8/16/24/32-bit PCM, μ-law, A-law, ADPCM, and IEEE float payloads. Converting WAV to AU is useful when:

• Java legacy code — the java.applet.AudioClip API and older javax.sound.sampled pipelines were designed around .au files; old applets and Java tutorials still ship sound effects as 8-bit, 8 kHz, μ-law AU clips.
• Unix/Solaris workflows — /dev/audio on SunOS/Solaris exposed μ-law natively, and many scientific computing and signal-processing pipelines on Unix still expect AU input.
• SoX, Octave, MATLAB, and Csound pipelines — .au is a first-class format in SoX (sox in.wav out.au) and is widely read by analysis tools where you want a known-byte-order container without RIFF chunk parsing.
• Smaller voice/telephony files — μ-law AU at 8 kHz mono runs about 8 KB per second versus 176 KB per second for a 16-bit/44.1 kHz stereo WAV — a reduction of more than 20×, which is fine for IVR prompts, voicemail, and speech corpora.
• Cross-platform interchange — AU's big-endian header and short fixed layout are easier to parse on embedded systems and retro hardware than RIFF/WAV's chunk-walking.

WAV vs AU — Format Comparison

Sample Rate and Channel Quick Guide

The converter's default AU encoding is 8-bit μ-law at whatever rate you choose — half the bytes of 16-bit PCM. The rows marked "PCM 16-bit" require selecting PCM_S16BE in the advanced options.

Frequently Asked Questions

Is WAV to AU lossless if I keep the same PCM format?

Only if you select 16-bit PCM (PCM_S16BE) in the advanced options — the converter's default AU encoding is 8-bit μ-law, a telephony-grade companding that is not bit-exact. With PCM_S16BE selected and Audio Channel and Sample Rate on "Original," a 16-bit PCM WAV's samples are carried into the AU container at full fidelity, just wrapped in Sun's header instead of RIFF chunks. Lossy reduction happens with the μ-law/A-law encodings or if you downsample or downmix.

Why would I want AU instead of WAV in 2026?

Mainly compatibility with software that predates modern formats: Java applets and tutorials, legacy Solaris/SunOS toolchains, scientific signal-processing scripts that read AU natively, and audio corpora distributed in .au for historical reasons (Sun's classic SPARCstation samples, several speech datasets). If you don't have one of those constraints, WAV, FLAC, or MP3 are usually better choices.

Will the AU output play in Windows Media Player or modern smartphones?

Not reliably. Windows Media Player, the iOS Files app, and Android's default audio apps don't ship AU support. To play an AU file on a modern desktop, use VLC, foobar2000, Audacity, or any player that bundles FFmpeg. On Unix, SoX (play file.au) and many distros' default media players handle it directly.

What sample rate should I pick for Java AudioClip compatibility?

The traditional Java java.applet.AudioClip interface was designed around 8-bit, 8 kHz, mono μ-law AU files. If you're feeding old applet code or a textbook example, set Audio Sample Rate to 8000 Hz and Audio Channel to Mono. Modern javax.sound.sampled can read 16-bit PCM AU as well, so for newer Java code you can keep CD-quality settings.

Does my WAV's bit depth carry over to the AU file?

Not by default — the converter writes 8-bit μ-law regardless of the source bit depth. To keep 16-bit samples, select PCM_S16BE (16-bit big-endian PCM) in the advanced options; big-endian byte order is what AU readers expect, so receiving software reads the samples correctly. 16-bit is the highest PCM depth this converter writes, so 24-bit WAV sources are rendered down to 16-bit rather than carried at 24-bit.

How big will my AU file be compared to the WAV?

With the default 8-bit μ-law output at the source's rate and channels, expect about half the size of a 16-bit WAV (one byte per sample per channel — 44.1 kHz stereo ≈ 88 KB per second, or ~5.3 MB per minute). If you select 16-bit PCM (PCM_S16BE) with the same sample rate and channels, the AU is essentially the same size as a 16-bit WAV — the headers differ by only a few dozen bytes. μ-law at 8 kHz mono drops to about 8 KB per second instead of 176 KB per second — less than 1/20 the size.

Can I batch-convert a folder of WAV files in one go?

Yes. Drop multiple .wav files onto the upload area and they queue up with shared settings. Each file is converted independently, so a failed file doesn't block the rest, and you can download them individually or as a zip when the batch finishes.

What if I need to go the other direction or pick a different output format?

Use our AU to WAV page for the reverse, WAV to MP3 when you need a small file for general playback, WAV to FLAC when you want lossless compression at roughly half the WAV's size, or the general Audio Converter to target a different codec entirely.

Is there a file size limit?

Free conversions handle typical music and speech WAVs without trouble. WAV itself caps at about 4 GiB because of the 32-bit size field in its RIFF header, so any source you upload is already within that ceiling. For very large multi-hour recordings, compress the WAV first or split it into segments before converting.