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FLVMP4

Convert FLV to MP4

This free FLV to MP4 converter changes your Flash Video (.flv) file into a MPEG-4 Part 14 (.mp4) file, right in your browser. There is nothing to install, no account to create, and no limit on how many files you convert.

100% private. Your file is processed locally in your browser with WebAssembly — it is never uploaded to a server, stored, or seen by anyone.

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The conversion runs on your own device using ffmpeg compiled to WebAssembly (ffmpeg.wasm), so your file is never uploaded to a server. MP4 is best for sharing and playing almost anywhere, which is the usual reason to convert from FLV.

Why convert FLV to MP4?

  • MP4 plays on more devices and apps than FLV, so it is the safer choice for sharing.
  • The video is re-encoded to efficient H.264, so the MP4 file is usually about the same size as your FLV.
  • Pick MP4 when you need a file made for sharing and playing almost anywhere.

FLV vs MP4

PropertyFLVMP4
Full nameFlash VideoMPEG-4 Part 14
ContainerFLVMPEG-4
Typical codecSorenson / VP6H.264 + AAC
CompatibilityVery limitedUniversal
Relative sizeSmallSmall
Best forLegacy Flash contentSharing and playing almost anywhere

How to convert FLV to MP4

  1. Add your FLV file

    Drag and drop your .flv file onto the upload area, or click to browse and pick it from your device.

  2. Start the conversion

    Click "Convert to MP4". Everything runs locally with ffmpeg compiled to WebAssembly (ffmpeg.wasm) - your file stays on your device.

  3. Wait a few seconds

    A progress bar shows the conversion. The first run is slightly slower while the engine loads, then it is cached.

  4. Download your MP4 file

    When it finishes, download the .mp4 file straight to your device.

Frequently asked questions

Is this FLV to MP4 converter free?
Yes. It is completely free with no signup, no watermark, and no limit on how many files you convert. It is supported by ads, which keeps the conversion itself free.
Are my files uploaded to a server?
No. The conversion runs locally in your browser using ffmpeg compiled to WebAssembly (ffmpeg.wasm), so your file is processed in memory on your own device and is never uploaded, stored, or seen by anyone.
Will I lose quality converting FLV to MP4?
The video is re-encoded to MP4 with a high-quality setting, so the result looks very close to the original FLV. Re-encoding is never bit-for-bit identical, but the loss is minimal.
Will the file get smaller or larger?
Usually similar. The video is re-encoded to H.264 at a high-quality setting, so the MP4 file is typically about the same size as your FLV; the container itself adds little.
What is the difference between FLV and MP4?
FLV is Flash Video (an FLV container, typically Sorenson / VP6); MP4 is MPEG-4 Part 14 (an MPEG-4 container, typically H.264 + AAC). MP4 is best for sharing and playing almost anywhere, while FLV is best for legacy Flash content.
How long does the conversion take?
Most files finish in a few seconds to under a minute, depending on length and your device. The first conversion is a little slower while the engine downloads and caches, then later runs start instantly.

Related conversions

MOV → MP4AVI → MP4MKV → MP4WebM → MP4WMV → MP4M4V → MP4

Need more formats or options? Use the full Change Video Format.