How do I convert MP3 to AAC?

This conversion re-encodes MP3 audio with the AAC codec, producing a raw .aac (ADTS) or MPEG-4-wrapped stream depending on the output settings. AAC is MP3's designed successor — standardised in MPEG-2/MPEG-4 — and is the required or preferred codec for HLS streaming, many broadcast pipelines, and video muxing workflows where an AAC track drops straight into an MP4 without re-encoding.

As a lossy-to-lossy transcode, quality can only go down slightly, so encode at or above the MP3's bitrate. AAC's efficiency advantage means an equal-bitrate AAC preserves the decoded signal at least as well as MP3 would, but it cannot restore anything the original MP3 encode discarded.

The most common real reason for this conversion is downstream tooling: preparing audio for HTTP Live Streaming, feeding an encoder that expects AAC input, or creating an audio track for video authoring. For simple playback, virtually everything that plays AAC also plays MP3, so conversion for its own sake is rarely needed.

Reasons to convert MP3 to AAC usually come down to compatibility, file-size, or specific feature requirements. Common situations:

• An app or platform only accepts AAC uploads.
• You need a feature unique to AAC (e.g. lossless editing, chapter markers, smaller streaming size, etc.) that MP3 doesn't provide.
• You're optimising file size — modern formats often produce smaller files than the older format you started with.
• You need a single archival format across a project so files behave consistently in the same viewer.

1. Open the MP3 → AAC tool on mp3.now.
2. Drag your MP3 file onto the drop zone, or click Select files. You can drop a whole folder of files at once.
3. The output is fixed to AAC. If the format supports extra options (bitrate, sample rate, channels, volume normalization), tweak them in the options panel.
4. Click Convert. The job runs on our server and finishes in a few seconds for typical tracks.
5. Download the result. Files stay in storage for 24 hours and are then permanently deleted.

The entire flow is free for the first 10 jobs per day with no signup required. A free account doubles that quota; a premium plan removes the limit entirely.

• Match or exceed the source MP3 bitrate — 192 kbps MP3 in, 192+ kbps AAC out.
• For an iTunes-friendly file with tags, choose MP3 to M4A instead; raw .aac streams carry no metadata.
• AAC-LC is the profile produced — the one video muxers and HLS expect.
• Don't transcode just for playback; convert only when a tool specifically requires AAC.
• Keep the MP3 original as your reference copy.