Step 1: Transfer your AAC files using the button above or by slide and deposit.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Retrieve your converted MP4 files.
AAC to MP4 Conversion FAQ
How do I convert an 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. AAC is Advanced Audio Coding, standardised in 1997 as MPEG-2 Part 7 and designed explicitly to replace MP3. MP4 is ISO/IEC 14496-14, standardised in 2001 and derived from the same QuickTime box layout MOV uses.
What will the picture be if I put AAC audio into an MP4 file?
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You choose it, because audio alone has no picture. The default is a static waveform render, and you can supply a still image instead — cover art, a title card, a photo — which is held for the whole duration. That is what makes the file uploadable to video-only platforms that will not accept a bare audio track. MP4 is the safest possible delivery target — every phone, browser, console, editor and Smart TV built in the last decade plays it without extra software.
Is the AAC audio re-encoded when it goes into the MP4?
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Only if it has to be. Where the MP4 container accepts the source audio codec directly, the stream is copied in untouched and stays bit-identical. Where it does not, the audio is transcoded once to whatever MP4 does accept, at a bitrate matched to the source so the second pass costs as little as possible. AAC is lossy but more efficient than MP3, and it handles up to 48 channels natively rather than being bolted onto a stereo design. Almost every MP4 in the wild is H.264 video with AAC audio; the container also legally holds HEVC, AV1 and VP9.
How large will the MP4 be compared with the AAC?
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Barely larger, if you use the default still image. A single held frame compresses to almost nothing across the whole duration because every frame is identical to the last, so the file is dominated by the audio track. Choosing an animated waveform instead adds real video data and can double or triple the result.
Do the artist and album tags on my AAC survive into the MP4?
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Partially. Title and artist map onto the video container’s own metadata fields, and embedded cover art is a natural fit for the still image the video displays. Everything else — track number, album, year, genre — has no equivalent slot in a video file and is dropped rather than approximated.
Will a surround mix in the AAC stay surround inside the MP4?
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Yes — MP4 carries multichannel audio properly, so a 5.1 mix stays 5.1 with the channel layout intact rather than being folded to stereo. That matters if the file is destined for a home cinema receiver rather than a phone, which will downmix at playback time anyway.
Is the AAC to MP4 converter free?
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Yes — basic AAC → MP4 conversion is free with no registration required. Premium adds higher per-file size limits, more parallel batch workers, longer retention, and removes ads.
How big an AAC file can I convert to MP4?
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Free accounts: up to 100 MB per AAC file. Premium: typically 1 GB per file depending on the source 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 the MP4 cannot represent (e.g. vector data in raster output, formulas in plain-text output) are rasterized or stripped — the result page lists what changed.
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 are queued in parallel. Premium runs 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 and 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 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 dependency — so even older browsers work to upload an AAC and download the MP4.
