Convert M4A to OPUS Online — Apple AAC to Modern Codec

OPUS delivers better compression than AAC with excellent quality at lower bitrates.

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

Drop M4A Files Here

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

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⚡ Median M4A → OPUS time (last 10k jobs): 1.4s per minute

How it works

1 · Drop your files
Drag & drop or choose M4A 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 OPUS files in seconds. Files delete automatically after 1 hour. Delete anytime after downloading with one click.

About M4A →

M4A (MPEG-4 Audio) is Apple's container format for AAC-encoded audio, introduced with iTunes in 2001. AAC itself was standardized by MPEG in 1997 (MPEG-2) and enhanced in 1999 (MPEG-4), achieving compression ratios of 8:1 to 12:1. M4A has become synonymous with Apple's ecosystem—it's the default for iTunes purchases, Apple Music downloads, and iPhone voice memos. At equivalent bitrates, AAC delivers better quality than MP3, with 256 kbps M4A typically matching 320 kbps MP3.

Learn more: M4A on Wikipedia

M4A supports sample rates up to 96 kHz and up to 48 audio channels, including surround sound configurations. The main limitation is compatibility—while modern devices handle M4A well, older hardware and some software (particularly on Windows and Linux) may not support it natively. For universal playback, MP3 remains the safer choice. M4A excels for Apple-centric workflows: syncing to iPhone, organizing in iTunes/Music app, or archiving Apple Music downloads.

About OPUS →

OPUS is a modern, open-source, royalty-free audio codec developed by Xiph.Org Foundation and IETF, standardized in RFC 6716 in September 2012. It was designed to replace both Vorbis (for music) and Speex (for voice), combining the best of both into a single codec. OPUS achieves exceptional quality at low bitrates—transparent quality at 128 kbps for music, and near-transparent voice at just 32 kbps. It supports bitrates from 6 kbps to 510 kbps and sample rates from 8 kHz to 48 kHz.

Learn more: Opus on Wikipedia

OPUS is the mandatory audio codec for WebRTC, making it the native format for video calls (Discord, Zoom, Google Meet, Teams) and voice messaging (WhatsApp, Telegram). It excels at both speech and music, adapting dynamically to content. OPUS files use the Ogg container (.opus extension) and play in all modern browsers (Chrome, Firefox, Edge, Safari 15+), VLC, and most media players from 2015 onward. For streaming, voice chat, podcasts, and any application where quality-per-bit matters, OPUS is the current state of the art.

Frequently Asked Questions

What is the difference between M4A (AAC) and OPUS?

M4A is Apple's audio container typically containing AAC (Advanced Audio Coding), while OPUS is a modern, open-source codec standardized by IETF. OPUS achieves equivalent quality at roughly half the bitrate of AAC, making files significantly smaller while being royalty-free.

Will converting M4A to OPUS reduce audio quality?

Technically yes, but usually imperceptible. Converting between lossy formats causes some quality loss. However, OPUS at 192 kbps (our default) is transparent quality—indistinguishable from the source in blind tests. If you have a lossless source, convert from that instead.

Why convert M4A to OPUS?

Smaller files and wider compatibility. OPUS offers better compression than AAC—same quality at lower bitrates. While M4A is tied to Apple ecosystem, OPUS is the mandatory codec for WebRTC (Discord, Zoom) and has excellent cross-platform browser support.

What bitrate does this converter use?

We encode OPUS at 192 kbps VBR (variable bitrate) by default, which provides transparent quality for music. At this bitrate, OPUS rivals 256 kbps AAC quality while producing smaller files.

Which devices and apps support OPUS?

OPUS has broad support: Chrome, Firefox, Edge, Safari 15+, all modern Android phones, VLC, foobar2000, MPV, and most streaming platforms. Apple devices (iOS 17+, macOS Sonoma+) now support OPUS natively.

What happens to metadata and album art?

Preserved! Text metadata (title, artist, album, genre) and embedded cover art transfer automatically. iTunes/Apple Music tags are converted to standard Vorbis comments used by OPUS.

Can I convert DRM-protected Apple Music files?

No. This converter only works with unprotected M4A files such as iTunes purchases made before 2009, DRM-free iTunes Plus purchases, or files you've ripped from CDs. Apple Music streaming tracks contain FairPlay DRM and cannot be converted.

How long can my audio files be?

Duration limits depend on your plan: Guest/Free: 120 minutes, Pro: 600 minutes (10 hours), Business: 3000 minutes (50 hours). Perfect for iTunes purchases, podcasts, or audiobooks.

What are the limits for this converter?

Tier	Max File Size	Max Files/Batch	Parallel Processing
Free	50 MB	50 files	3 at once
Pro	500 MB	200 files	6 at once
Business	2048 MB	1000 files	10 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 (minimum)
6-10 minutes: 2 credits
11-15 minutes: 3 credits
16-20 minutes: 4 credits

Example: A 10-minute file = 1 credit. 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
Free	50 credits/day	—
Pro	—	10,000 credits/month
Business	—	30,000 credits/month

Daily credits (Free tier, including guests) reset every day at midnight UTC. Monthly credits (Pro & Business) 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 10,000 audio files per month.

Answers at a Glance

Quick answers to common questions.

Choose Your Plan

Limits shown for M4A to OPUS conversion. One subscription unlocks the entire Tools.FAST Network. Plans cover Convert.FAST, Compress.FAST, PDF.FAST (soon), and all future tools.

Monthly Annual 4 Months Free

Free

For occasional personal use

50 MB per file
50 files per batch
3 parallel conversions
50 credits/day
Standard priority
Email support

No sign-up required. Create an account for your own credit pool.

Popular

Pro

$9 /month

For independent work

500 MB per file
200 files per batch
6 parallel conversions
10,000 credits/month across Tools.FAST
High priority
Email & chat support
One subscription for the entire Tools.FAST network

Business

$19 /month

1 seat

For production scale

2 GB per file
1000 files per batch
10 parallel conversions
30,000 credits/month across Tools.FAST
Add seats to invite team members
Highest priority
Priority email & chat support
One subscription for the entire Tools.FAST network

How Credits Work

Usually 1 credit per conversion. Exact cost shown before you start.
Credits refresh monthly on your billing cycle.
Unused credits roll over, capped at your plan's monthly amount.
One subscription, all sites. Works across Convert.FAST, Compress.FAST, and future tools.

View all converter limits by tier →

What's New in M4A to OPUS

Latest improvements to this converter

Last updated December 22, 2025

Dec 22, 2025

Initial release of M4A to OPUS converter with high-quality OPUS encoding.