Convert FLV to MP4
Convert FLV files to MP4 entirely in your browser — no upload, no account, no watermark.
Your file never leaves your device — conversion runs entirely in this browser tab.
To convert FLV to MP4, open the MP4 converter and drop your FLV file in. The conversion runs entirely inside your browser using WebAssembly, so the file is never uploaded. FLV is effectively dead, so this is usually an archive-rescue job.
What to expect from this conversion
FLV is effectively dead, so this is usually an archive-rescue job. The video inside is often H.264 already, which keeps quality loss modest. Very old FLV files hold Sorenson Spark video, which looks poor no matter what you convert it to.
The Flash video container. Effectively obsolete since Flash was retired, but persists in older downloads and archives.
Lossy · video
The universal container, normally holding H.264 and AAC. Plays essentially everywhere.
Lossy · video
Both FLV and MP4 discard data to save space, so this conversion compresses something that has already been compressed. Always convert from your original file rather than from an earlier conversion — the losses compound.
How to do it
- Open the MP4 converter
Go to the MP4 converter and drop your FLV file onto it, or click to browse.
- Convert
Press Convert. FFmpeg runs in your browser and shows real progress as it works.
- Download
Download the finished MP4 file. It is created in your browser and never sent anywhere.
Common questions
How do I convert FLV to MP4?
Open the MP4 converter, drop your FLV file onto it and press Convert. Everything runs in your browser — the file is not uploaded. Desktop browsers handle files up to about 200MB; mobile browsers about 40MB.
Does converting FLV to MP4 lose quality?
Yes, some. Both FLV and MP4 are lossy, so this is a second compression pass over data that was already compressed. The loss is usually modest, but always convert from your original rather than from a previous conversion.
Is it free to convert FLV to MP4?
Yes, with no account, no watermark and no daily limit. The processing happens on your device rather than on a server, so there are no per-conversion costs to pass on.
Are my files uploaded when converting FLV to MP4?
No. FFmpeg runs as WebAssembly inside your browser tab. The file is read from your disk, processed in memory and written back out — it never reaches a server.