Step 1: Attach your MP3 files using the button above or by bring and position.
Step 2: Click the 'Optimize' button to start the optimization.
Step 3: Collect your converted AAC files.
MP3 to AAC Optimization FAQ
How do I convert MP3 audio to AAC without losing quality?
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Upload the MP3 file and our converter picks a AAC codec / bitrate combination matched to the source. Lossless target (AAC = WAV / FLAC / ALAC) preserves every sample; lossy target (AAC = MP3 / AAC / OGG / Opus) defaults to 192 kbps which is transparent for most ears.
What bitrate does the AAC file use?
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Default 192 kbps for lossy AAC; pass-through (no bitrate dial) for lossless AAC. Override to 320 kbps for audiophile output, or 96 kbps for voice / podcast where smaller files matter more than fidelity at the extremes.
Will going from MP3 to AAC reduce my audio quality?
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If MP3 is lossy and AAC is lossless (e.g. MP3 -> WAV), the AAC file is no better than the MP3 — you cannot recover information that was already thrown away. If MP3 is lossless and AAC is lossy, the AAC codec recompresses; at 192 kbps this is transparent for most content.
Does the MP3 to AAC converter keep ID3 / metadata tags?
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Yes — title, artist, album, year, track number, and embedded album art are read from MP3 and written into the AAC container where the AAC format supports tags (which all common ones do).
Can I batch convert hundreds of MP3 files to AAC?
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Yes — drop a folder of MP3 files in and we process them in parallel. Pro 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?
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By default yes (48 kHz MP3 -> 48 kHz AAC). If you need to downsample for compatibility (e.g. 96 kHz -> 44.1 kHz for CD burning) the advanced sample-rate option handles this with a high-quality polyphase resampler.
Can I normalize loudness in the MP3 to AAC step?
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Yes — the loudness-normalize option applies ITU-R BS.1770 / EBU R128 normalization to the AAC output, targeting -14 LUFS (streaming standard) or -16 LUFS (podcast standard). Useful when batch-converting tracks with varying mastering levels.
Will the AAC play on my car stereo / iPod / Sonos?
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MP3 plays universally. AAC plays on Apple, most Android, and Sonos. FLAC plays on Sonos and modern Android, less well on older iPods. WAV plays on everything but is huge. The advanced options include device presets for these common targets.
Is my MP3 file private during conversion?
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Yes — uploaded MP3 files are processed in isolated workers and deleted within minutes. We never play, store, or share audio content. See /privacy/ for the data retention window.
How long does converting a 1-hour MP3 to AAC take?
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Same-codec re-mux: 10-30 seconds. Re-encode to a different codec: typically 10-20% of source duration, so a 1-hour MP3 -> AAC finishes in 6-12 minutes on the standard pipeline.
Why is the AAC file louder / quieter than the MP3 source?
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No automatic gain change happens unless you turn on the normalize option. If you do see a level change, your audio player or media library is probably applying ReplayGain or per-track normalization on playback — not us.
Can I convert MP3 downloads to AAC?
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If the MP3 download is unprotected (no DRM), yes. DRM-encrypted streaming files (Spotify, Apple Music) are encrypted at the bit level and we cannot process them. Sources from Bandcamp, SoundCloud, and personal recordings convert fine.