Step 1: Attach your AAC files using the button above or by bring and position.
Step 2: Click the 'Optimize' button to start the optimization.
Step 3: Collect your converted MP4 files.
AAC to MP4 Optimization FAQ
How do I convert a AAC file to MP4?
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Upload your AAC file using the picker above and the converter detects the source type and runs the AAC -> MP4 pipeline. The result downloads automatically when conversion completes; no account needed for one-off conversions.
Is the AAC to MP4 converter free?
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Yes — basic AAC -> MP4 conversion is free with no registration. Pro adds higher per-file size caps, more parallel batch workers, removes ads, and unlocks API access for MP4 output.
How big a AAC file can I convert to MP4?
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Free accounts: up to 100 MB per AAC file. Pro: typically 1 GB per file, depending on the AAC type. Very large files are split into chunks server-side when the MP4 format allows.
Will conversion change the content of my AAC?
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Conversion preserves all information that both AAC and MP4 can represent. Format-specific features that MP4 does not support (e.g. vector data in raster output, formulas in plain-text output) are rasterized or stripped — see the format-specific notes on the result page.
Can I convert many AAC files to MP4 at once?
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Yes — drop multiple AAC files into the upload zone and they queue in parallel. Pro has more parallel workers; on a 50-file batch this is the difference between minutes and seconds.
Does the AAC to MP4 converter work on phones / tablets?
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Yes — the UI is responsive and the conversion pipeline runs server-side, so mobile devices upload-then-download just like desktops. iOS and Android browser file pickers (camera roll, Files app) work end-to-end.
Which browsers does the AAC to MP4 converter support?
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Chrome, Firefox, Safari (15+), Edge, and Opera. The converter uses standard `<input type="file">` upload — no WebAssembly or PWA dependencies — so even older browsers work.
Are my AAC files kept private?
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Yes — uploaded AAC files are processed in isolated workers and deleted within minutes. We never view, retain, or share content. See /privacy/ for the data-retention window.
What if the MP4 download does not start automatically?
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Disable any pop-up blocker, then click the download button manually. The result link stays active for 24 hours, so if your network fails mid-download you can re-trigger from the result page without re-uploading the AAC.
How long does AAC to MP4 conversion take?
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Typically seconds for small files, a minute or two for files near the size cap. Server-side pipeline runs on dedicated workers — your laptop CPU is not the bottleneck.
Do I need to install software to convert AAC to MP4?
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No — the converter runs entirely in your browser plus our servers. No desktop install, no plugin, no extension. Just upload, wait, download.
Can I convert AAC to MP4 without an account?
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Yes for one-off conversions. Sign up free for batch history, server-side file storage, and higher conversion limits. Pro adds parallel workers, bigger file caps, and removes ads.