Does converting FLAC to M4A lose quality?

Yes. M4A uses the AAC codec which is lossy — the encoder permanently discards audio information that psychoacoustic models consider inaudible. At 256 kbps, most listeners cannot distinguish the result from the original FLAC. At 128 kbps, the difference may be noticeable on high-end headphones or speaker systems. Once converted, you cannot recover the lost data, so keep the original FLAC if archival quality matters.

What bitrate should I choose for FLAC to M4A?

128 kbps is adequate for casual listening on earbuds or laptop speakers. 192 kbps is a good general-purpose choice that balances quality and file size. 256 kbps is recommended for music where fidelity matters or for Apple Music distribution. AAC is more efficient than MP3, so 256 kbps AAC sounds comparable to 320 kbps MP3.

What is the FFmpeg command for FLAC to M4A?

The basic command is: ffmpeg -i input.flac -c:a aac -b:a 256k -map_metadata 0 output.m4a. Replace 256k with your chosen bitrate. The -c:a aac flag selects the AAC encoder, and -map_metadata 0 copies tags (artist, title, album) from the FLAC file into the M4A container.

Is my FLAC file uploaded anywhere?

No. The metadata inspector uses the Web Audio API entirely in your browser. Your file is read into browser memory only and is never transmitted to any server. Refreshing the page clears all data.

How much smaller will the M4A be compared to the FLAC?

A typical FLAC file is 20–40 MB per album track. At 256 kbps M4A, a 4-minute track is roughly 7–8 MB. At 128 kbps it drops to about 3.8 MB. The exact size depends on duration — you can use the formula: size (MB) = bitrate (kbps) x duration (seconds) / 8000.

Can I convert multiple FLAC files at once?

Yes, using a shell loop. On Linux/macOS: for f in *.flac; do ffmpeg -i "$f" -c:a aac -b:a 256k -map_metadata 0 "${f%.flac}.m4a"; done. On Windows PowerShell: Get-ChildItem *.flac | ForEach-Object { ffmpeg -i $_.FullName -c:a aac -b:a 256k -map_metadata 0 ($_.BaseName + ".m4a") }

What is the difference between M4A and AAC?

Both use the AAC audio codec. M4A is an MPEG-4 container (.m4a file extension) that holds the AAC audio stream along with metadata tags like title, artist, album, and cover art. A raw .aac file is a bitstream without a container and has limited tag support. For music and Apple devices, .m4a is the preferred format.

FLAC to M4A Converter

Inspect your FLAC file metadata in the browser and generate the perfect FFmpeg command to convert it to M4A (AAC) at your chosen bitrate.

Inspect FLAC Metadata

Drop a FLAC (or any audio) file to read its properties. Nothing is uploaded.

Drop FLAC file here or click to browse FLAC, WAV, OGG, MP3 accepted

FFmpeg Command Generator

AAC Bitrate

Copy metadata tags from source (-map_metadata 0)

ffmpeg -i input.flac -c:a aac -b:a 256k -map_metadata 0 output.m4a

Install FFmpeg free at ffmpeg.org. Replace input.flac with your actual filename.

Batch convert (Linux / macOS)

for f in *.flac; do ffmpeg -i "$f" -c:a aac -b:a 256k -map_metadata 0 "${f%.flac}.m4a"; done

GUI alternatives

iTunes / Apple Music — import FLAC (via third-party), export M4A natively on macOS
fre:ac — free, open-source, Windows / macOS / Linux, supports AAC/M4A output
dBpoweramp — paid, batch conversion with AAC encoder on Windows / macOS
VLC — free media player with a basic convert/transcode feature for M4A output

Drop a FLAC file on the left to inspect its metadata

No file is uploaded — everything runs in your browser

AAC Bitrate Reference

Bitrate	Quality	Size / min	Best For
96 kbps	Acceptable	~0.7 MB	Voice, speech, podcasts
128 kbps	Good	~0.9 MB	Earbuds, laptop speakers
192 kbps	Very Good	~1.4 MB	General music listening
256 kbps	Transparent	~1.9 MB	Apple Music distribution, audiophile

AAC is more efficient than MP3: 128 kbps AAC is roughly equivalent in perceptual quality to 160–192 kbps MP3.

FLAC vs. M4A — At a Glance

FLAC (Lossless)

Bit-perfect reproduction of source
Preferred for DAWs and archival storage
Supports 24-bit / hi-res audio
Large files (20–40 MB per track)
Not natively supported on iOS or Apple devices

M4A / AAC (Lossy)

Native support on all Apple devices and iOS
Small file size (4–9 MB per track at 128–256 kbps)
Used by Apple Music, YouTube, and streaming platforms
Discards audio data permanently
Re-encoding degrades quality further

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Summary

FLAC is a lossless audio format that preserves every bit of the original recording, but its large file sizes are impractical for Apple devices, streaming services, and casual sharing. M4A uses the AAC codec inside an MPEG-4 container — the same format used by Apple Music, iTunes, and most iOS apps — and achieves smaller files while maintaining excellent perceptual quality. This tool lets you drop any FLAC file to inspect its sample rate, duration, and channels, choose an AAC bitrate that matches your quality needs, then copy a ready-to-run FFmpeg command to do the actual conversion. Everything runs in your browser; no file is ever uploaded.

How it works

Drop a FLAC file onto the inspector panel (or click to browse).
The Web Audio API reads the file's sample rate, duration, and channel count locally.
Choose an AAC bitrate — 128 kbps for casual listening, 192 kbps for good quality, 256 kbps for high fidelity.
Copy the generated FFmpeg command and run it in your terminal.
Verify the output M4A in a player before deleting your original FLAC.

Use cases

Shrink a FLAC music library for Apple devices, iPhone, or iPod with limited storage.
Prepare audio tracks for iTunes, Apple Music, or iOS app submissions that require AAC.
Convert a FLAC podcast or audiobook to M4A for car or earphone playback.
Batch-convert an album by adapting the single-file command into a shell loop.
Check a FLAC file's sample rate and duration before encoding.
Estimate the output M4A file size before committing to a bitrate.
Generate a ready-to-paste FFmpeg command without memorizing its flags.
Compare FLAC and M4A characteristics side-by-side before deciding on a format.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu