Step 1: Supply your FLV 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.
FLV to MP4 Conversion FAQ
What does the FLV to MP4 converter do?
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FLV is a legacy container, often poorly supported on modern devices. Converting to MP4 rewraps the video with a current codec (H.264 / H.265 / VP9) for broad browser, phone, and TV compatibility.
Will resolution and frame rate be preserved in the MP4?
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Yes. FLV → MP4 keeps resolution, frame rate, and aspect ratio unchanged by default. To change them, use the Resize or Speed tool on the result.
Will the FLV play smoothly on modern devices after converting to MP4?
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Yes. Legacy FLV files often fail to play in modern browsers and on iOS / Android. MP4 uses widely supported codecs that play natively on phones, tablets, smart TVs, and every modern browser.
Will the converted MP4 be a different size than the FLV?
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Modern codecs compress better, so MP4 from a legacy FLV is typically 30-60% smaller at equivalent quality. Conversions in the opposite direction can grow the file.
Can I add selectable subtitles once the file is MP4?
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Yes. FLV has no usable soft-subtitle track, so subtitles for FLV content had to be burned into the picture or shipped as a separate sidecar file. MP4 carries subtitles as their own selectable stream, so after conversion you can attach an SRT track the viewer can switch on, switch off or restyle. Almost every MP4 in the wild is H.264 video with AAC audio; the container also legally holds HEVC, AV1 and VP9.
Will the MP4 play on a phone without anything installed?
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That is the whole argument for it. MP4 is what phones record to and what every phone, tablet, console, television and browser built in the last decade decodes in hardware, so a file in it opens on whatever the recipient happens to own. Hardware decoding is the part people underestimate: it is why an hour of video plays on a phone without draining the battery, and why nothing else is a safer choice when you do not know what the file will land on. 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.
Will the MP4 play in a browser when the FLV would not?
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Yes, and that is usually the whole reason for the conversion. An FLV embedded in a web page either shows a broken player or forces a download, because browsers ship no decoder for it. MP4 plays inline through the native HTML5 video element with no plugin and no external application.
Is it worth converting old FLV recordings to MP4 at all?
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For anything you intend to keep, yes. FLV belongs to an earlier generation of video tooling and the software that reads it is steadily disappearing from phones, browsers and operating systems. Moving the footage to MP4 now, while a clean decoder still exists, is the difference between an archive you can open in ten years and one you cannot. No current browser, phone or TV can play FLV — anything still in this container has to be moved out of it to remain watchable.
Is there a file-size limit when converting FLV 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 FLV files to MP4 at once?
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Yes. Drop or pick multiple FLV 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.
What happens to my FLV files after the conversion?
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Uploaded files and MP4 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.
Will my MP4 play on phones, tablets, and TVs?
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Yes — MP4 uses modern codecs that play natively on iOS, Android, Smart TVs, game consoles, and every modern browser.
