Add your AAC file
Drop one or more .aac files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
AAC to M4R
Re-encoding .aac audio as .m4r changes how the sound is compressed and which players will accept it. Free, private, and validated — the file never leaves your browser.
100% private for supported formats
Runs on your deviceConvert supported files
Drop AAC files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting AAC audio to Apple ringtone
Re-encoding .aac audio as .m4r changes how the sound is compressed and which players will accept it. An .aac file holds raw Advanced Audio Coding data, usually as an ADTS stream. AAC was designed as MP3's successor and delivers audibly better quality at the same bitrate, though the bare .aac extension is rarer than AAC audio traveling inside .m4a or .mp4 files.
An .m4r file is an iPhone ringtone: AAC audio in an MPEG-4 container, identical to an .m4a in everything but the extension. Apple uses .m4r purely as a routing marker so iTunes and iOS file the audio under Tones instead of Music. For this route the practical draw is the only ringtone format iOS accepts and full AAC quality, indistinguishable from the source track — balanced against tones over 40 seconds are rejected outright, which is worth knowing before you commit a large batch.
Why convert AAC to M4R?
The practical trigger for this conversion is usually a mismatch: with .aac, raw ADTS files handle tags and cover art poorly. Switching to .m4r buys you the only ringtone format iOS accepts, which is why it is the better fit for turning a favorite song's hook into a custom iPhone ringtone. Because the conversion runs locally, trying it costs nothing but a few seconds of compute on your own machine.
AAC vs M4R at a glance
| Aspect | AAC audio (.aac) | Apple ringtone (.m4r) |
|---|---|---|
| Format type | Lossy — discards detail it judges invisible to shrink files | Lossy — discards detail it judges invisible to shrink files |
| How it stores data | a pure MDCT transform codec, free of the hybrid filterbank compromise that limited MP3 | shares the ISO base media layout of .m4a, carrying AAC-LC audio |
| Strongest at | receiving the audio track copied out of MP4 video without re-encoding | turning a favorite song's hook into a custom iPhone ringtone |
| Weak spot | raw ADTS files handle tags and cover art poorly | tones over 40 seconds are rejected outright |
| Metadata | no standard tag container exists for raw ADTS streams; ID3 tags are sometimes prepended but poorly supported, so wrapping in .m4a is the reliable way to tag AAC | standard iTunes atoms apply, though iOS shows only the title in the ringtone picker |
Pick M4R as the output
Select .m4r in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if M4R is selectable, the route is real and validated.
Convert on your device
Press Convert. The transcode runs on an FFmpeg engine compiled to WebAssembly, so the audio never leaves your device.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid M4R file. Outputs keep the original filename with the .m4r extension.
AAC to M4R questions, answered
Will converting AAC to M4R lose quality?
A second lossy step always costs a little, because aac is lossy-oriented and m4r is lossy-oriented and each encoder discards detail differently (generation loss). At the default quality the difference is rarely visible; avoid repeated round-trips between .aac and .m4r.
Is it private to convert AAC files here?
Yes — the .aac file is processed inside your browser tab and never uploaded. The transcode runs on an FFmpeg engine compiled to WebAssembly, so the audio never leaves your device. Close the tab and the file is gone from memory.
Where will the M4R file work?
iPhones accept .m4r only through iTunes or Finder sync and GarageBand export, and every Apple device can play it since the audio is ordinary AAC. Other platforms open the file happily after a rename, though Android sources its ringtones from plain MP3 or OGG instead.
Will the M4R file be bigger or smaller than my AAC?
It depends on the content: shares the ISO base media layout of .m4a, carrying AAC-LC audio. Convert one representative file first and compare before batch-processing a large set.
What happens to the metadata in my AAC file?
This converter strips container metadata deliberately (the FFmpeg command runs with metadata mapping disabled) so exported files do not leak recording details. In the source, no standard tag container exists for raw ADTS streams; ID3 tags are sometimes prepended but poorly supported, so wrapping in .m4a is the reliable way to tag AAC; none of it is transmitted anywhere because the file never leaves your browser.
Can I convert M4R back to AAC?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .aac → .m4r → .aac is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.