Convert legacy FLV Flash videos to MP4 so they play in modern browsers and phones. Drop a .flv file below and the output is already set to MP4.
1
Drag and drop your .flv file onto the box above, or click Choose Files. The request is already filled in: “Convert this to MP4”.
2
The AI assistant uses sensible defaults. To choose the resolution, frame rate or bitrate yourself, say so in the request, for example “Convert this to MP4 in 720p”.
3
The assistant opens with your file and converts it on your own device; the file itself is never uploaded. When the MP4 file is ready, click Save. Prefer to set everything by hand, or batch-convert several files into a ZIP? The classic converter is one click away on this page.
Flash is gone, and with it every browser's ability to play FLV. Converting FLV to MP4 rescues old downloads, screencasts and web videos into a format that plays anywhere and uploads to YouTube, Drive or social media.
Most FLV files carry H.264 video with AAC or MP3 audio. The converter reads the FLV in your browser: H.264 video is copied into the MP4 unchanged when you keep the default settings, or re-encoded when you change them: by your browser's hardware video encoder, or by FFmpeg on your CPU for an FLV over 512 MB or in a browser that cannot encode AAC audio. Older FLV video is re-encoded to H.264 by FFmpeg. Nothing is uploaded.
FLV (Flash Video): FLV (Flash Video) was the streaming format of the Flash era. Modern browsers no longer play it, so FLV files usually need converting before they can be watched or edited. It is best for legacy Flash-era archives.
MP4 (MPEG-4 Part 14): MP4 is the most widely supported video container in the world. It usually carries H.264 or H.265 video with AAC audio, plays on every phone, browser, TV and editing app, and is the safest choice for sharing. It is best for sharing, social media, web playback and mobile devices.
In short: keep FLV when the priority is legacy Flash-era archives, and switch to MP4 when the file is headed for sharing, social media, web playback and mobile devices. Need a different target? The full Video Converter supports every format listed below.
FLV files with H.264, Sorenson Spark (H.263) or VP6 video are all read by the in-browser FFmpeg build. At the default settings H.264 is copied into the MP4 as is; Sorenson Spark and VP6 are re-encoded to H.264.
For an H.264 FLV at the default settings, yes: the picture is copied, not re-encoded. Older codecs, or a lower resolution or bitrate, mean a re-encode; keep the resolution and a bitrate at or above the source to stay visually close to the original.
Yes. Converting FLV to MP4 on Convertor.video is free, with no watermark and no sign-up. The AI assistant runs on a free daily allowance of assistant credits; the classic converter on this page has no daily limit at all.
No. The conversion runs inside your browser using WebCodecs and FFmpeg compiled to WebAssembly, so your .flv file is read and converted on your own device and never uploaded, which keeps private recordings private and means there is no waiting in an upload queue. The AI assistant only sees what you type and basic facts about the file: its name, format, duration and size.
There is no plan or account limit, but the converter loads the whole FLV file into your browser's memory, so about 2 GB per file is the practical ceiling; larger files may fail to open. At the default settings an H.264 FLV's picture is copied as is; change the resolution, frame rate or bitrate and your browser's hardware (WebCodecs) re-encodes it (FFmpeg does, on your CPU, for an FLV over 512 MB or in a browser that cannot encode AAC audio). Older FLVs with Sorenson Spark or VP6 video cannot be decoded by the browser, so those run entirely in FFmpeg on your CPU and take noticeably longer.
Yes. Ask the AI assistant for a resolution, frame rate or bitrate in your request. Audio and subtitle track selection, the codec list and every other setting are in the classic converter, one click away on this page.
It is built and tested on current desktop Chrome and Edge, which are also fastest because they expose hardware-accelerated WebCodecs video decoders. Recent Firefox and Safari releases support the same web APIs; if a file fails there, try Chrome or Edge.