Convert FLAC to M4A (AAC) Online
Convert lossless FLAC to M4A (AAC) for the Apple ecosystem. Free, in your browser, no file uploads.
.flac · up to 100 MB
What you can do
FLAC to M4A: lossless to the Apple standard at optimal quality
Native Apple Music
M4A with AAC imports directly into iTunes and Apple Music without additional steps.
100% private
Your music never leaves your device. Local conversion without servers.
256 kbps transparent
The same bitrate Apple uses in its iTunes Music catalog. Quality practically indistinguishable from the original.
Optimal chain
Lossless→lossy is the superior encoding chain. No accumulated artifacts.
How it works
Three steps, no hassle
Upload your FLAC file
Drag or select your .flac file. No signup or installs required. Up to 500 MB.
Optimal browser-side conversion
The lossless FLAC is decoded to PCM and re-encoded to AAC in an M4A container — the optimal encoding chain for the Apple ecosystem.
Download your M4A
File compatible with iTunes, Apple Music, iPhone, iPad, Apple Watch, AirPods, and every Apple device.
FAQ
Got questions?
Because it starts from the best possible source. FLAC is lossless: it contains exactly the same audio as the CD or studio master, without any degradation. When re-encoding that perfect PCM to AAC, the AAC codec operates on maximum quality material, without the accumulated artifacts it would have if the audio had first passed through MP3 or another lossy codec. The lossless→lossy chain is always superior to lossy→lossy, because each additional lossy compression generation accumulates artifacts. FLAC→AAC at 256 kbps produces the best possible AAC at that bitrate, extracted from the original audio without intermediate degradation.
The default bitrate is 256 kbps AAC, which is the bitrate Apple uses for its iTunes/Apple Music catalog (excluding Apple Lossless). At 256 kbps, AAC (Advanced Audio Coding, defined in ISO/IEC 13818-7 in 1997 and improved with HE-AAC in 2003) achieves perceptual transparency for virtually all musical content, meaning that in blind listening tests (ABX) the vast majority of listeners cannot distinguish the AAC from the original FLAC. This transparency was documented in EBU (European Broadcasting Union) listening test studies and is the basis for Apple's decision to use 256 kbps as their standard bitrate.
AAC (Advanced Audio Coding) is the audio codec — the compression algorithm. M4A is the container: a variant of the MP4 container (ISO Base Media File Format) specialized for audio, with the .m4a extension used by Apple since iTunes to distinguish MP4 audio files from MP4 video files. Technically, M4A is an MP4 containing only AAC audio tracks. The .m4a extension ensures iTunes, Apple Music, iPhone, and iPad recognize the file as audio rather than video.
Yes. M4A with AAC is the native format of iTunes and Apple Music. You can import the file directly by dragging it into iTunes or Apple Music, and it will be added to your library without any additional steps. It is also compatible with sync to iPhone and iPad via iTunes/Finder, and with AirPlay for playback on HomePod, Apple TV, and AirPlay speakers.
FLAC uses Vorbis Comment as its metadata system (TITLE, ARTIST, ALBUM, TRACKNUMBER, etc.), while M4A uses iTunes Tags (©nam, ©ART, ©alb, trkn atoms, etc.). Metadata is converted between systems: the TITLE field in Vorbis Comment maps to the ©nam iTunes Tag atom, ARTIST to ©ART, ALBUM to ©alb, and so on. The album artwork (if included in the FLAC as a PICTURE block) is also transferred to the M4A's covr atom.
M4A with AAC offers better quality than MP3 at the same bitrate. At 128 kbps, MP3 produces audible artifacts in many musical genres; AAC at 128 kbps offers quality equivalent to MP3 at 192 kbps. At 256 kbps, AAC achieves practical transparency, while MP3 at 256 kbps still produces minor artifacts in high-frequency material (cymbals, high strings). Additionally, M4A is the standard format of the Apple ecosystem: it has hardware acceleration on all Apple chips (A-series, M-series) and native support without external codecs on all Apple devices since 2003.
Convert FLAC to M4A: lossless to the Apple standard at the best possible quality
FLAC (Free Lossless Audio Codec) was developed by Josh Coalson and released in stable version 1.0 on July 20, 2001 under the BSD license, with the goal of offering patent-free lossless audio compression as an alternative to Shorten and the proprietary ALAC (Apple Lossless) format. FLAC uses variable-order Linear Predictive Coding (LPC) to model the audio signal, compresses the residuals with Rice-Golomb coding, and includes MD5 checksums in metadata for integrity verification. The result is typical 40–60% compression compared to WAV without discarding a single bit: a FLAC decoded to WAV is bit-for-bit identical to the original WAV. M4A is Apple's audio file format based on the MP4 container (ISO Base Media File Format, ISO/IEC 14496-12), introduced by Apple with iTunes 4 in 2003 as the standard format for iTunes Music Store downloads. M4A uses AAC (Advanced Audio Coding, defined in ISO/IEC 13818-7 in 1997) as its audio codec, the technical successor to MP3 with better compression efficiency and superior quality at the same bitrate. Converting FLAC to M4A represents the optimal encoding chain for anyone who needs a compact audio file compatible with the Apple ecosystem: starting from the highest quality material possible (lossless FLAC, without any prior degradation) and applying AAC lossy compression exactly once, with no accumulation of multi-generation compression artifacts.
The technical superiority of the FLAC→AAC chain over other conversion routes (such as MP3→AAC or OGG→AAC) is explained by the principle of compression generations. Each lossy codec permanently discards information: audio output from a lossy codec no longer has all the information from the original. If that lossy audio is re-encoded with another lossy codec, the second codec operates on already-degraded material and discards additional information relative to the previous degraded version, not relative to the original. The result is artifact accumulation: artifacts from the first codec plus artifacts from the second codec, superimposed. With FLAC as the source, the AAC codec always operates on the perfect original PCM, without prior artifacts. The standard target bitrate is 256 kbps AAC, which is the bitrate Apple has used for its entire iTunes Music Store (now Apple Music) catalog since 2012, when Apple replaced its 128 kbps DRM-free files with 256 kbps DRM-free files in the iTunes Plus program. At 256 kbps, AAC achieves documented perceptual transparency: in EBU Tech 3335 listening tests (conducted with demanding reference material including strings, cymbals, solo voices, and chamber music), AAC at 256 kbps consistently scores above the transparency threshold for 85% of trained listener panelists. Hydrogenaudio studies and evaluation tool results from fre:ac (formerly BonkEnc) confirm that 256 kbps AAC is effectively transparent for 95% of listeners on 95% of musical material.
The practical reasons for converting FLAC to M4A in 2025 are directly tied to the Apple ecosystem and its compatibility constraints. FLAC, despite being an excellent format with broad support on open platforms, has limited native support in the Apple ecosystem: Apple Music on iOS (until iOS 11) did not natively support FLAC, and although iOS 11 added FLAC playback support in 2017 and macOS Mojave extended it in 2018, FLAC integration into the Apple Music library remains imperfect — it cannot always be synced to iPhone via Finder, and Apple Watch does not support FLAC for offline storage. M4A with AAC has none of these limitations: it is the native format of the entire Apple ecosystem with perfect support on iPhone, iPad, Apple Watch, HomePod, Apple TV, and full synchronization via iCloud Music Library. For users with music collections in FLAC who want to integrate them fully into the Apple ecosystem (including sync to portable devices and offline playback on Apple Watch), converting to M4A is the definitive solution. Convertir.ai performs the conversion entirely in the browser via WebAssembly, without sending audio files to any external server. No registration is required and there are no usage limits.