Step 1: Supply your FLAC files using the button above or by haul and lay.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Get your converted Opus files.
FLAC to Opus Conversion FAQ
What does the FLAC to OPUS audio converter do?
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FLAC is lossless audio; OPUS is lossy. The converter re-encodes the waveform at a configurable bitrate. The result is much smaller but discards some inaudible frequency content — usually transparent at 192 kbps+.
What bitrate should I pick for OPUS?
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320 kbps for archival quality, 256 kbps for transparent listening on most speakers, 192 kbps for streaming, 128 kbps when file size dominates. Below 96 kbps artifacts become audible on percussive content.
Is the FLAC to OPUS conversion reversible?
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You can convert the OPUS back to FLAC on this site. If either format involved is lossy, the round-trip is not bit-perfect even though it is visually or audibly close.
How much smaller will the OPUS be than my FLAC?
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Typically 5-10x smaller for images, 5-15x smaller for audio. Exact ratio depends on the chosen quality level and the content — flat solid-colour images and silent audio compress far more than detailed photos or busy soundtracks.
How much quality do I lose converting FLAC to OPUS?
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Some, and it is permanent — this is the one direction where information is genuinely thrown away. FLAC holds every sample exactly; OPUS discards what a psychoacoustic model predicts you will not hear. At 192 kbps and above that prediction is good enough to be transparent on most material and most equipment. Keep the FLAC as your master, because you cannot get back to it from the OPUS. FLAC uses linear prediction plus Rice coding to reach roughly 50-60% of the original size while decoding back to bit-identical PCM. Opus scales from 6 kbps mono speech to 510 kbps stereo music in the same bitstream and switches modes automatically.
What exactly is an OPUS file?
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A container with the audio inside it, rather than the audio on its own. That extra layer is where the length, the seek index and whatever metadata the format defines are kept, so a player knows how long an OPUS is before decoding a single frame instead of scanning the whole file to find out. It also means the extension does not always settle what is inside: several containers of this kind are allowed to hold more than one sort of audio, which is why two OPUS files can behave differently while looking identical from outside.
Most of my FLAC files came from CDs — does that matter here?
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Only in that the encode already happened once. A FLAC ripped from a disc was compressed at whatever bitrate the ripper was set to years ago, and that is the ceiling on everything downstream — converting cannot recover what the ripper discarded. If the discs are still on a shelf, re-ripping to a lossless format and encoding from that gives a genuinely better result than any conversion of the existing files. FLAC is the Free Lossless Audio Codec, an open format from 2001 that compresses without discarding a single sample.
Is FLAC free to use and distribute?
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Yes, without conditions worth worrying about. The specification is public, anyone can implement an encoder or decoder without asking or paying, and nobody can change those terms later — which is why it turns up in open-source tooling, in game engines and anywhere a licence negotiation would have killed the project. Converting away from it does not undo that; the files you already have stay exactly as usable as they were.
Is OPUS too new for the things I need to play it on?
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That is the one real risk with it. OPUS is a recent codec and it is genuinely better than the older ones at the same bitrate — noticeably so below 96 kbps — but "better" is not "supported", and a car head unit, a standalone player or a television from before it existed will simply not recognise the file. Browsers, phones and computers are fine. Check the oldest device that has to play it and choose on that, not on the numbers. Opus is almost never supported by standalone hardware — assume software playback only, and expect car stereos to ignore it.
Is there a file-size limit when converting FLAC to OPUS?
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Anonymous uploads are capped at a generous default; signed-in free accounts get a higher cap, and Pro accounts have no per-file limit. Browser memory is usually the practical constraint long before our server-side limits kick in.
Can I batch-convert several FLAC files to OPUS at once?
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Yes. Drop or pick multiple FLAC files in one upload — the converter processes them in parallel and returns a ZIP of the OPUS results. There is no need to repeat the upload step per file.
What happens to my FLAC files after the conversion?
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Uploaded files and OPUS outputs are auto-deleted after a short retention window. We do not inspect, share, or train on user files. Direct download links are time-limited and tied to your session.
