Bulk Convert MP3 to AAC Online — Raw ADTS Format

Convert MP3 to AAC (ADTS) for streaming and hardware device compatibility.

Drop up to 50 files at once — no install, no sign-up required.

Drop MP3 Files Here

50 MB or 2 hours per file Up to 50 files (2 GB limit) 3 parallel conversions 1 credit per 5 minutes

Encrypted EU Servers Auto-delete 1h

⚡ Median MP3 → AAC time (last 10k jobs): 894ms per minute

How it works

1 · Drop your files
Drag & drop or choose MP3 files. No account required—paid plans unlock bigger batches, higher limits, and priority queues.
2 · We convert securely
Processed on our dedicated servers. Encrypted in transit & at rest. We never store filenames—only file types & sizes for accounting.
3 · Download & auto-delete
Grab your AAC files in seconds. Files delete automatically after 1 hour. Delete anytime after downloading with one click.

About MP3 →

MP3 (MPEG-1 Audio Layer III) revolutionized digital audio when it was standardized in 1993 by the Fraunhofer Society. Using psychoacoustic compression, MP3 removes audio frequencies that humans typically cannot perceive, achieving 10:1 compression or better while maintaining excellent subjective quality. MP3 supports sample rates from 8-48 kHz and 16-bit audio. At 256 kbps, most listeners cannot distinguish MP3 from the original source in blind tests.

Learn more: MP3 on Wikipedia

MP3 remains the most universally compatible audio format, supported by every music player, smartphone, computer, and web browser. While newer codecs like AAC and Opus offer marginally better compression efficiency, MP3's ubiquitous support makes it the safest choice for sharing audio. The format's patents expired in 2017, making it completely free to use without licensing concerns.

About AAC →

AAC (Advanced Audio Coding) is the successor to MP3, standardized by MPEG in 1997 and subsequently adopted as the default format for YouTube, Apple Music, and most streaming platforms. Achieving compression ratios of 8:1 to 12:1, AAC delivers better quality than MP3 at the same bitrate—128 kbps AAC typically matches 160-192 kbps MP3. It's the underlying codec in M4A files (AAC audio in an MP4 container) and the audio component of most video files.

Learn more: AAC on Wikipedia

Raw AAC files (with .aac extension) are less common than containerized versions (.m4a, .mp4), but they're used in broadcast, streaming pipelines, and as extracted audio from video. AAC supports sample rates up to 96 kHz and up to 48 audio channels, including 5.1 and 7.1 surround configurations—making it suitable for professional multichannel content. For maximum compatibility with minimal quality loss, AAC at 256 kbps is often the sweet spot between MP3's universality and FLAC's fidelity.

Frequently Asked Questions

What is the difference between MP3 and AAC?

MP3 uses older MPEG-1 Layer 3 compression. AAC (Advanced Audio Coding) is a more modern codec that generally achieves better quality at the same bitrate. AAC is widely supported across devices and streaming platforms.

What is ADTS AAC format?

ADTS (Audio Data Transport Stream) is raw AAC with sync headers added to each frame. Unlike M4A which wraps AAC in an MP4 container, ADTS AAC is a raw bitstream format. This makes it ideal for streaming applications, hardware devices, and broadcast systems that need direct access to audio frames.

What is the difference between AAC and M4A?

M4A is AAC audio wrapped in an MPEG-4 (MP4) container. AAC (ADTS) is raw AAC data without a container. M4A supports metadata, chapters, and artwork while raw AAC is simpler and more compatible with streaming. Need the container version? Convert MP3 to M4A instead.

Will converting MP3 to AAC improve audio quality?

No, it won't improve quality. Since MP3 is already compressed, converting to AAC re-encodes the audio. You get a different codec, but the quality lost during original MP3 encoding is gone forever. For best quality, start from lossless FLAC sources instead.

Why would I convert MP3 to AAC?

Compatibility and streaming. Some hardware devices, broadcast systems, and streaming protocols specifically require raw AAC/ADTS format. AAC is also more efficient than MP3, so it's preferred for bandwidth-constrained applications. For Apple devices and iTunes, MP3 to M4A may be a better fit.

What AAC settings do you use?

We encode at 256 kbps AAC using a high-quality encoder with ADTS output format. This provides excellent audio quality suitable for most use cases.

How long can my audio files be?

Duration limits depend on your plan: Guest/Free: 120 minutes, Pro: 3000 minutes (50 hours). This accommodates everything from short clips to full audiobook chapters and podcasts.

What are the limits for this converter?

Tier	Max File Size	Max Files/Batch	Parallel Processing
Guest/Free	50 MB	50 files	3 at once
Pro	2048 MB	1000 files	6 at once

Note: File size limits are specific to this converter. Batch and parallel processing limits apply to all images converters site-wide. See all converter limits →

How are credits calculated for this conversion?

Cost: 1 credit per 5 minutes

How it works:

Files up to 5 minutes: 1 credit
6-10 minutes: 2 credits
11-15 minutes: 3 credits
16-20 minutes: 4 credits

Example: A 10-minute file = 2 credits. A 180-minute (3h) audiobook = 36 credits.

Why per-minute? Audio conversion time scales with content duration, not file size. Longer audio requires proportionally more processing.

What are my daily and monthly credit limits?

Credit allocations vary by account tier:

Tier	Daily Limit	Monthly Limit
Guest	100 credits/day	—
Free	100 credits/day	—
Pro	—	12,000 credits/month

Daily credits (Guest & Free tiers) reset every day at midnight UTC. Monthly credits (Pro) reset on your billing cycle date.

Note: With 1 credit per 5 minutes, audio files under 5 MB cost 1 credit each. Pro users can convert 12,000 audio files per month.

Answers at a Glance

Quick answers to common questions.

What's New in MP3 to AAC

Latest improvements to this converter

Last updated December 20, 2025

Dec 20, 2025

Initial release of MP3 to AAC converter with raw ADTS AAC output.

Need to get more done? Pro starts from $5.

1 GB files 1,000 per batch Priority queue Web + API

See Pricing →

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