Convert FLV to MP4, Free
Upload your FLV file and get a MP4 in seconds. No account, no watermark.
How to convert FLV to MP4
FLV (Flash Video) was the dominant web video format through the 2000s and early 2010s, used by YouTube, Vimeo, and countless streaming sites before HTML5 video took over. With Adobe Flash no longer supported in any modern browser, FLV files are now unplayable without special software. Converting to MP4 gives you a file that plays natively on any current device.
BoltConverter re-encodes your FLV to H.264 MP4 on its servers. The audio and video streams are decoded from FLV and written into the standard MP4 container. Most FLV files contain H.263 or VP6 video and MP3 or AAC audio, all of which convert cleanly to H.264 MP4.
Upload your FLV file
Click the upload area or drag your .flv file onto the page. The file is transferred over an encrypted connection.
Conversion runs on the server
The server decodes the FLV video and audio and re-encodes them into an H.264 MP4 file.
Download the MP4
Save the MP4 to your device. It will play in any modern media player or browser.
Frequently asked questions
Why can I no longer play FLV files?
FLV relied on Adobe Flash Player, which all major browsers removed in 2020 and 2021. Without Flash, FLV files do not play in browsers. Converting to MP4 solves this.
Will video quality be affected?
Re-encoding always involves some quality trade-off. BoltConverter uses settings that produce good quality at a reasonable file size, but if your original FLV is already low quality, the MP4 will reflect that.
How large can my FLV file be?
There is a file size limit shown on the upload page. Most archived FLV clips from the Flash era fall well within it.
Does the converter keep the original audio track?
Yes. The audio from the FLV is decoded and included in the MP4, maintaining sync with the video.
Can I play the converted MP4 on my phone?
Yes. H.264 MP4 is the most widely supported video format on Android and iOS devices.