Step 1: Share your MP3 files using the button above or by drag and drop.
Step 2: Click the 'Transform' button to start the transformation.
Step 3: Grab your converted AAC files.
MP3 to AAC Transformation FAQ
How do I convert MP3 audio to AAC without losing quality?
+
Upload the MP3 file and the converter chooses the AAC codec and bitrate to match the source. Lossless AAC (WAV / FLAC / ALAC) preserves every sample bit-identically; lossy AAC (MP3 / AAC / OGG / Opus) defaults to 192 kbps which is transparent for most ears. MP3 is lossy: a psychoacoustic model discards frequencies the ear is unlikely to notice, typically at 128 to 320 kbps. AAC is lossy but more efficient than MP3, and it handles up to 48 channels natively rather than being bolted onto a stereo design.
Is converting MP3 to AAC a second round of lossy compression?
+
Yes, and it is worth planning around. Both formats are lossy, so the AAC encoder is working from audio that has already been through one psychoacoustic pass, and its own decisions compound the first set. At 192 kbps or above the result is still transparent for most listening. If you have a lossless master anywhere, encoding the AAC from that instead avoids the double pass entirely.
What bitrate will the resulting AAC file use?
+
Default is 192 kbps for lossy AAC; pass-through for lossless AAC. Override to 320 kbps for audiophile or 96 kbps for voice / podcast. The choice trades file size against audible fidelity; below 96 kbps lossy artifacts become noticeable on music.
Will going from MP3 to AAC reduce my audio quality?
+
If MP3 is lossy and AAC is lossless (e.g. MP3 → WAV), the AAC is no better than the MP3 — you cannot recover information already discarded. If MP3 is lossless and AAC is lossy, the AAC codec recompresses; at 192 kbps the result is transparent for most content.
Does the MP3 to AAC converter keep ID3 / metadata tags?
+
Yes — title, artist, album, year, track number, and album art are read from the MP3 container and written into the AAC container where the format supports tags. All common targets (MP3, AAC, FLAC, OGG) handle tags fine; raw WAV does not. AAC is Advanced Audio Coding, standardised in 1997 as MPEG-2 Part 7 and designed explicitly to replace MP3.
Can I batch convert hundreds of MP3 files to AAC?
+
Yes — drop a folder of MP3 files in and we process them in parallel. Premium has more parallel workers and no per-file size cap, so a 500-file batch finishes in minutes rather than tens of minutes.
Will the AAC keep the same sample rate as MP3?
+
By default yes — 48 kHz MP3 stays 48 kHz in AAC. If you need to downsample for compatibility (96 kHz → 44.1 kHz for CD burning), the sample-rate option applies high-quality resampling in the same encode pass.
Can I normalize loudness when converting MP3 to AAC?
+
Yes — the loudness-normalize option applies ITU-R BS.1770 / EBU R128 normalization to the AAC, targeting -14 LUFS (streaming standard) or -16 LUFS (podcast standard). Useful when batching tracks mastered at varying levels.
Will my AAC play on car stereo, iPod, and Sonos?
+
MP3 plays everywhere. AAC plays on Apple, most Android, and Sonos. FLAC plays on Sonos and Android but not on older iPods. WAV plays on everything but is huge. The advanced device-preset dropdown picks an AAC codec optimized for your target hardware. AAC sounds noticeably better than MP3 below 128 kbps and is the default audio track in MP4, YouTube, Apple Music and broadcast. AAC is patent-encumbered, and a handful of very old players still refuse it where they would accept an MP3.
Is my MP3 file private during conversion to AAC?
+
Yes — uploaded MP3 files are processed in isolated workers and deleted within minutes. We never play back, store long-term, or share the audio content. The full retention window is in /privacy/.
How long does converting a 1-hour MP3 to AAC take?
+
Same-codec re-mux: 10 to 30 seconds. Re-encode to a different codec: typically 10 to 20% of source duration, so a 1-hour MP3 → AAC finishes in 6 to 12 minutes. Batch jobs parallelize across workers for further speedups.
Why is the AAC louder or quieter than the MP3 source?
+
No automatic gain change happens unless you enable the normalize option. If you observe a level change, your audio player or media library is likely applying ReplayGain or per-track normalization on playback — not us. Disable that to hear the true AAC levels.
