Audio to FLAC Converter

How to Convert Audio to FLAC

1. Upload Your Audio File: Drag and drop onto the page or click "Add Files". The converter accepts AAC, AC3, AIF, AIFC, AIFF, AMR, AU, DSS, FLAC, M4A, M4B, MP3, OGA, OGG, Opus, VOC, WAV, WebA and WMA, and you can queue a batch that all runs with the same settings.
2. Set the Compression Level: The Compression level slider runs 1 to 12 and sits at 12. Every level produces identical audio — a higher number spends more encoder time hunting for redundancy and shrinks the file slightly further, with no effect on playback.
3. Set Audio Channel, Sample Rate, or Trim (Optional): Audio Channel and Audio Sample Rate both default to "ORIGINAL", which is what you want for an archive. Override them only to fold surround down to stereo or to hit a target rate. Trim starts on "Unchanged" and takes a start time plus a duration.
4. Convert and Download: Click Convert and save the FLAC. Files travel over an encrypted connection, are processed on our servers, and are deleted automatically a few hours later. No sign-up, no watermark.

Popular FLAC Conversions

• WAV to FLAC — the classic win: identical audio in roughly half the space, plus tags and a built-in integrity check
• MP3 to FLAC — a stable editing master when the MP3 is the only copy you still have
• AIFF to FLAC — shrink Apple/pro-audio PCM masters without touching a single sample value
• M4A to FLAC — pull AAC-in-MP4 tracks out of the Apple ecosystem into an open container
• WMA to FLAC — retire a Windows Media library into a format that is not tied to one platform
• AU to FLAC — modernise legacy Sun/NeXT recordings with checksums and metadata attached
• OGG to FLAC — move Vorbis audio to its lossless sibling in the same Xiph family
• AC3 to FLAC — get Dolby Digital soundtrack audio into an open, tag-friendly container

Why Convert to FLAC?

FLAC — Free Lossless Audio Codec — is the open, royalty-free lossless format maintained by the Xiph.Org Foundation, and it was formally standardised by the IETF as RFC 9639, a Proposed Standard published in 2024. "Lossless" is the whole pitch: the decoded waveform is mathematically identical to the PCM that went in, so you can re-encode, re-tag, and edit forever without accumulating artifacts.

The honest caveat most converters skip is that lossless only preserves. It never restores. Feed FLAC an MP3 and you get a bigger file containing exactly the same audio the MP3 already had, missing everything the MP3 encoder threw away years ago. So there are two genuinely good reasons to convert here, and one bad one:

• Shrink an uncompressed master. WAV, AIFF and AU are raw PCM. FLAC typically packs them to roughly 40–60% of their original size with zero quality change, which is the single most common reason people run this conversion.
• Get tagging and integrity checking. WAV is notoriously bad at metadata. FLAC carries proper Vorbis comments and stores an MD5 checksum of the unencoded audio in its STREAMINFO block, so a decoder can prove years later that the file has not silently rotted.
• Not a quality upgrade. Converting MP3, AAC or WMA to FLAC produces a larger file that sounds exactly like the source. It is worth doing only when you want a stable master to edit against, never as a fidelity boost.

What FLAC Does to Your Source — Format by Format

FLAC Format at a Glance

Frequently Asked Questions

Does converting MP3 to FLAC improve the sound quality?

No, and nothing can. MP3, AAC, OGG, Opus and WMA are lossy — the encoder permanently discarded audio data, and no later step can rebuild it. Converting a 128 kbps MP3 to FLAC gives you a considerably larger file that sounds exactly like the MP3. FLAC is still worth it as an editing master, because every subsequent edit, EQ pass or re-export on a lossy file compounds artifacts while FLAC stays clean. To genuinely improve quality you have to go back to the CD, the session, or another lossless original.

Which sources actually get smaller when converted to FLAC?

Only uncompressed ones. FLAC losslessly packs raw PCM — WAV, AIFF, AU — down to roughly 40–60% of its original size depending on how busy the material is; quiet acoustic recordings compress far better than dense loud mixes. It cannot squeeze an already-compressed MP3 or AAC any further, so wrapping a lossy stream in FLAC adds overhead and produces a file larger than the source while sounding identical. The format-by-format table above lists the outcome for every accepted input.

What compression level should I pick?

For an archive, leave it at 12. Higher levels change encode time only — the decoded audio is identical at every setting, and playback CPU does not rise with the level, so there is no runtime penalty for choosing the maximum. The returns are asymptotic: most of the compressible redundancy is already captured by level 5, and each step above 8 typically buys another percent or two. Drop the slider only if you are batch-converting a very large library and encode time matters more than the last few percent of size.

Is FLAC really lossless, and how would I know a decade later?

Yes, mathematically so — the decoder reconstructs the exact PCM sample values that went in. FLAC also solves the "is this old file still intact?" problem better than most formats: every FLAC stores a 128-bit MD5 checksum of the unencoded audio in its STREAMINFO block, a feature written into the format's IETF specification, RFC 9639. A decoder can recompute that checksum years later and flag corruption even when the bitstream itself still parses cleanly. WAV and MP3 have no equivalent.

What input formats can I convert to FLAC here?

Nineteen in all: AAC, AC3, AIF, AIFC, AIFF, AMR, AU, DSS, FLAC, M4A, M4B, MP3, OGA, OGG, Opus, VOC, WAV, WebA and WMA. Lossless sources become a smaller, verifiable FLAC; lossy sources become a faithful FLAC copy of the same audio at a larger size. If you would rather end up with uncompressed PCM for a DAW, the audio to WAV converter takes the same input list and writes WAV instead.

Should I keep multichannel audio or downmix to stereo?

It depends on where the file is going. Phones, laptops and headphones all output stereo, so a stereo FLAC is more portable and roughly half the size of a 5.1 mix. Keep the original layout when you are archiving surround mixes or concert recordings for a home-theatre setup — FLAC handles up to 8 channels natively, so there is no technical reason to fold them down. The Audio Channel control lets you force Mono or Stereo, or leave "ORIGINAL" to pass the source layout through untouched.

Will resampling to 44100 Hz or 48000 Hz hurt anything?

It can, so avoid it unless you have a reason. Leaving Audio Sample Rate on "ORIGINAL" keeps the file a faithful copy. Choosing a different rate forces a resample, which is a real signal-processing step and therefore not lossless even though the FLAC container still is. Set 44100 Hz only when a CD-oriented tool demands it, or 48000 Hz when the audio is destined for a video timeline. Upsampling an 8 kHz voice recording to 48 kHz adds bytes and no detail whatsoever.

Does FLAC keep my track titles, artist and album art?

Yes, and this is often the real reason to leave WAV behind. FLAC stores metadata as Vorbis comments and can embed cover art in a dedicated picture block, so titles, artists, albums, track numbers and artwork all survive in the file itself. What it cannot do is invent metadata that the source never had — a bare WAV or a legacy AU carries little or nothing to copy across, so expect to fill those fields in afterwards in a tag editor.

Will my files be kept or shared after I convert?

No. Your upload travels over an encrypted connection, is processed on our servers, and is deleted automatically a few hours after conversion. Files are never shared and never made public, there is no account to create, and nothing is watermarked. If you later want to go the other way and produce a compressed copy, FLAC to MP3 and FLAC to WAV handle the reverse.