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 MP4 files.
FLAC to MP4 Conversion FAQ
What does the FLAC to MP4 converter do?
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It converts a FLAC file into MP4 format.
Will the data inside my FLAC be preserved when converting to MP4?
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Yes — the content is mapped to the MP4 equivalent. Format-specific extras that MP4 does not represent natively are omitted rather than corrupted.
Is the FLAC to MP4 conversion reversible?
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You can convert the MP4 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 MP4 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.
What will the picture be if I put FLAC audio into an MP4 file?
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You choose it, because audio alone has no picture. The default is a static waveform render, and you can supply a still image instead — cover art, a title card, a photo — which is held for the whole duration. That is what makes the file uploadable to video-only platforms that will not accept a bare audio track. FLAC is the Free Lossless Audio Codec, an open format from 2001 that compresses without discarding a single sample. MP4 is the safest possible delivery target — every phone, browser, console, editor and Smart TV built in the last decade plays it without extra software.
Is the FLAC audio re-encoded when it goes into the MP4?
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Only if it has to be. Where the MP4 container accepts the source audio codec directly, the stream is copied in untouched and stays bit-identical. Where it does not, the audio is transcoded once to whatever MP4 does accept, at a bitrate matched to the source so the second pass costs as little as possible. FLAC uses linear prediction plus Rice coding to reach roughly 50-60% of the original size while decoding back to bit-identical PCM. Almost every MP4 in the wild is H.264 video with AAC audio; the container also legally holds HEVC, AV1 and VP9.
My FLAC is lossless — does putting it in an MP4 throw that away?
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It usually does, because video containers expect a compressed audio track and most players will not accept raw PCM inside one. The audio is encoded once, at a high bitrate so the loss is inaudible, and the lossless FLAC stays untouched on your side. Keep it: it remains the master, and the MP4 is a delivery copy. FLAC gives you WAV fidelity at half the size, with proper metadata tags and embedded artwork, which is why it dominates lossless music libraries.
How large will the MP4 be compared with the FLAC?
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Barely larger, if you use the default still image. A single held frame compresses to almost nothing across the whole duration because every frame is identical to the last, so the file is dominated by the audio track. Choosing an animated waveform instead adds real video data and can double or triple the result.
Do the artist and album tags on my FLAC survive into the MP4?
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Partially. Title and artist map onto the video container’s own metadata fields, and embedded cover art is a natural fit for the still image the video displays. Everything else — track number, album, year, genre — has no equivalent slot in a video file and is dropped rather than approximated.
Will a surround mix in the FLAC stay surround inside the MP4?
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Yes — MP4 carries multichannel audio properly, so a 5.1 mix stays 5.1 with the channel layout intact rather than being folded to stereo. That matters if the file is destined for a home cinema receiver rather than a phone, which will downmix at playback time anyway.
Is there a file-size limit when converting FLAC to MP4?
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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 MP4 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 MP4 results. There is no need to repeat the upload step per file.
