Step 1: Drop your AAC files using the button above or by deposit and leave.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Receive your converted MKV files.
AAC to MKV Conversion FAQ
How do I convert an AAC file to MKV?
+
Upload your AAC file using the picker above and the converter detects the source type and runs the AAC → MKV pipeline. The result downloads automatically when conversion completes; no account needed for one-off conversions.
What will the picture be if I put AAC audio into an MKV file?
+
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. AAC is Advanced Audio Coding, standardised in 1997 as MPEG-2 Part 7 and designed explicitly to replace MP3. MKV is the archival container of choice because it stores unlimited audio tracks, soft subtitles, chapter markers and cover art in one file.
Is the AAC audio re-encoded when it goes into the MKV?
+
Only if it has to be. Where the MKV 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 MKV 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. MKV is codec-agnostic: H.264, HEVC, VP9 and AV1 video sit happily beside AAC, FLAC, Opus, DTS or Dolby audio in the same file.
How large will the MKV be compared with the AAC?
+
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 MKV?
+
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 MKV?
+
Yes — MKV 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 MKV converter free?
+
Yes — basic AAC → MKV conversion is free with no registration. Premium adds higher per-file size limits, more parallel batch workers, and removes ads.
How big an AAC file can I convert to MKV?
+
Free accounts: up to 100 MB per AAC file. Premium: typically 1 GB per file, depending on the AAC source type. Very large files are split into chunks server-side when the MKV format allows.
Will conversion change the content of my AAC?
+
Conversion preserves all information that both AAC and MKV can represent. Format-specific features that the MKV format doesn't 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 MKV at once?
+
Yes — drop multiple AAC files into the upload zone and they are queued in parallel. Premium has more parallel workers; on a 50-file batch this is the difference between minutes and seconds.
Does the AAC to MKV converter work on phones and tablets?
+
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 MKV converter support?
+
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.
