Convert FLV to MP4 online
Rescue a years-old FLV (Flash) video and convert it to MP4, playable on any device today, without uploading the file to any server.
Convert FLV to MP4
Your file is processed right in this browser: it never gets uploaded to any server.
Why use PullVid for FLV → MP4?
Conversion details
How do you convert an FLV to MP4?
Choose the FLV file you want to convert to MP4.
Hit 'Convert'. If the video uses an old Flash codec it gets re-encoded and may take longer; if it's already H.264/AAC, it's nearly instant.
Download the resulting MP4; it saves straight to your device.
If you have a years-old video saved in FLV format and almost nothing plays it anymore, this converter rescues it into MP4 without touching the video whenever it can, right in your browser and without uploading the file to any server.
Why do I have FLV videos that won't play properly?
FLV was, for years, the dominant video format on the internet: YouTube used it before 2015, Flash players embedded on web pages relied on it, and a large chunk of downloads from that era are stuck in it. Adobe discontinued Flash Player in 2020 and browsers pulled support, so almost no modern player opens an FLV directly anymore. MP4 is today's universal equivalent.
How it works: remux or re-encoding, depending on the codec
We use ffmpeg compiled to WebAssembly. If your FLV already carries H.264 video and AAC or MP3 audio — common in more recent FLVs — we do an instant remux with no re-encoding. If the video uses older Flash codecs, like Sorenson Spark or VP6 (common in FLVs more than 10-15 years old), the converter automatically re-encodes them to H.264/AAC so the resulting MP4 plays anywhere.
Steps to convert your FLV to MP4
- Choose the FLV file from your device ('Choose file' button).
- Hit 'Convert'. The first time, your browser downloads the conversion engine (a few MB); after that, it's faster.
- Wait for the progress bar to hit 100% (seconds for a remux, longer if it re-encodes).
- Download the resulting MP4 with the 'Download result' button.
Which old Flash codecs we re-encode
Older FLVs usually carry video in Sorenson Spark or VP6 and audio in MP3 or the less common Nellymoser: none of those video codecs are supported by the MP4 container without re-encoding. The converter detects them and automatically converts them to H.264 (video) and AAC (audio), the standards that guarantee playback on any device today.
Honest limits worth knowing
Since the process runs in your browser, the real limit is your device's memory and processing power, not an artificial cap of ours. FLVs that need re-encoding because they carry old Flash codecs can take several minutes if they're long, especially on phones with limited RAM — try a computer if that happens. This converter processes one file at a time, on a single thread.
Other related conversions
If your video is already in MP4 and you want a container with more room for subtitles and audio tracks, try MP4 to MKV. For other old formats, check our guide how to convert a video to MP4. If you don't have the video yet, use our YouTube video downloader.
Related articles
Convert a video to MP4: how to download it already in this format
Need a video in MP4? With PullVid you download it straight in MP4, the most compatible format. No conversion software: paste the link, pick MP4, and you're done.
MP4, WebM, MKV: Which Video Format to Choose When Downloading
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MP4 vs MKV: which format to choose when downloading a video
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Frequently asked questions about FLV → MP4
What's an FLV file, and where does it usually come from?
FLV (Flash Video) was the standard video format on the web for years: YouTube used it before 2015, Flash players embedded on web pages relied on it, and plenty of downloads from that era are still in this format. If you have videos saved from a good while back, there's a decent chance they're FLV.
Why can't I play my old FLV videos properly anymore?
Because Adobe discontinued Flash Player in 2020 and browsers dropped support for it, so very few modern players open an FLV natively today. Converting it to MP4 makes it playable on any current phone, TV or program.
Do I lose quality converting an FLV to MP4?
It depends on the video. If it already uses modern codecs (H.264/AAC or MP3, common in more recent FLVs), it's a lossless remux. If it uses old Flash codecs like Sorenson or VP6, re-encoding is required, which means a small quality loss but it's the only way to get MP4 to play it.
Is there a size or length limit on the FLV video?
We don't set an artificial limit, but the process runs in your browser: long FLV videos that need re-encoding can take several minutes, especially on phones with limited RAM. The ones that can be remuxed directly are nearly instant.
I don't have the FLV file yet — can I download it here?
This converter works with an FLV file you already have saved, from an old download or recording, say. If instead you want to download a current video, use our YouTube video downloader, which delivers directly in MP4.