Convert MP3 to AAC
MP3 re-encoded as a bare AAC stream — for the tools that ask for .aac, made on your own device.
Drop your video or audio here
or
MP4, MOV, WebM, MKV, AVI, MP3, WAV and more — any size, no upload
🔒 Files never leave your device — everything runs in your browser.
A tool that asks for a .aac file wants a raw AAC stream — the format of broadcast systems, streaming encoders, and some embedded devices. It is AAC without a container: no M4A wrapper, just the audio frames, which is exactly what those systems ingest.
The conversion decodes the MP3 and re-encodes it as AAC at high quality in your browser. Both formats are lossy, so convert once and keep the original; done that way, the result stays audibly identical while satisfying whatever pipeline insisted on .aac. Nothing uploads in the process.
How it works
- Drop your file
Any common format, any size. Nothing is uploaded — the tool runs in your browser.
- Convert
Compatible files are repackaged instantly with zero quality loss; others are hardware-transcoded at high quality.
- Download
Your converted file is ready on your device — nothing to wait for, nothing to delete from a server.
Frequently asked questions
What is the difference between .aac and .m4a?
The same audio family, different packaging — .m4a wraps AAC in a container with metadata and seeking; .aac is the bare stream. Some broadcast and embedded tools want the stream form specifically, which is what this page produces.
Does converting MP3 to AAC lose quality?
A lossy-to-lossy conversion always costs a little in theory; at the high-quality bitrate used here the difference is inaudible in practice. Keep the MP3 original and avoid repeated back-and-forth conversions.
Why does my .aac file show no duration in some players?
Raw streams carry no index, so players estimate — that is a property of the format, not a conversion error. If you want normal seeking and metadata, convert to M4A instead.
Is my file uploaded to a server?
No. ConvertUno runs entirely in your browser on your own device. Your file never leaves your computer or phone — there is no upload at all.
Is it really free, with no watermark?
Yes. Processing happens on your device, so serving you costs us almost nothing — no watermark, no account, no file-size limit, no daily quota.