MP4 to FLV Converter
Convert MP4 to FLV in your browser. Free, no signup. Conversion files are not uploaded to Format Convertly servers. Learn the formats, then convert when your workflow needs FLV.
Choose a file or drag and drop
Drop your MP4 file here or
Choose file · Drag & drop · Public file link
- Processed on your device
- No conversion file stored on our servers
- Maximum file size: 100 MB
Conversion runs in your browser. Files are not uploaded to Format Convertly servers.
Processed on your device
No conversion file stored on our servers
Conversion Settings
Customize the output to match your needs.
Convert Quality
92%Output
Output options for this format are applied automatically during browser conversion. Drop your file above to begin.
Advanced settings
Additional Options
Quality or bitrate forces a re-encode. Width/FPS apply only when creating GIF or animated WebP.
How to Convert MP4 to FLV
Add your MP4
Drop a MP4 file into the browser panel. Nothing is sent to a remote queue.
Confirm settings
Review optional quality/size settings, then confirm FLV as the output.
Download FLV
Convert locally and download the FLV file when processing finishes.
Why Convert MP4 to FLV?
Private by design
MP4 → FLV runs in your browser. Files are not uploaded to a remote conversion queue.
Ready for the next step
Convert when a site, editor, or teammate expects FLV instead of MP4.
Practical quality
FLV: lossy (legacy Flash codecs / H.264 in later FLV). Lossy targets trade size for speed — preview when it matters.
Wide compatibility
MP4 is commonly used for Social uploads and Website video.
MP4 vs FLV
A quick side-by-side before you convert — deeper comparison lives on the full guide.
| Feature | MP4 | FLV |
|---|---|---|
| Kind | multimedia container | video container |
| Compression | lossy (codec-dependent) | lossy (legacy Flash codecs / H.264 in later FLV) |
| Lossy / lossless | Typically lossy | Typically lossy |
| Transparency | Not supported / N/A | Not supported / N/A |
| Best for | Social uploads; Website video | Recovering old Flash-era recordings; Archival course videos from the 2000s–2010s |
| Typical size | Large vs audio; efficient vs uncompressed video | Varies; many old FLVs are low-resolution lecture captures |
| Browser / web support | Excellent HTML5 video support | Flash is gone — convert to MP4 for HTML5 |
| Compatibility | The default video container for phones, social platforms, smart TVs, and HTML5 players — safest modern delivery choice | Legacy only — modern browsers will not play FLV without conversion; VLC can open many archives before you remux to MP4 |
Choose MP4 when…
- Social uploads
- Website video
- Phone playback
- Client delivery from editors
Choose FLV when…
- Recovering old Flash-era recordings
- Archival course videos from the 2000s–2010s
- Migrating legacy learning libraries
- One-time modernization to MP4
What happens to video quality?
FLV compatibility: Legacy only — modern browsers will not play FLV without conversion; VLC can open many archives before you remux to MP4
Tip
Converting from MP4 cannot restore detail already removed by lossy compression.
Does MP4 to FLV reduce quality?
FLV is typically lossy (lossy (legacy Flash codecs / H.264 in later FLV)). Use a higher bitrate when fidelity matters, and keep the MP4 master for archival.
FLV format guide →Should I keep the original MP4?
Yes when you may need to re-encode later. MP4: MP4 is the safest video delivery format for phones, web, and social platforms. Shoot or edit in whatever your camera prefers, then provide an MP4 derivative for sharing.
MP4 format guide →MP4 · FLV
Related converters MP4
Related converters FLV
Frequently Asked Questions
More on quality loss: conversion quality guides · problem-solution guides
Does converting MP4 to FLV reduce quality?
It can — both sides are typically lossy. A careful encode may look similar; repeated re-encodes cause generational loss. Prefer converting once from the best master you have.
Can you recover quality after converting?
Not from a lossy output alone. Return to the original master (or a better source). Converting to a lossless format does not resurrect discarded detail.
What is generational loss?
Damage that stacks when you decode and lossy-encode the same file over and over (for example JPG→edit→JPG). Edit from masters and export delivery formats once.
Where can I learn more about conversion quality?
Browse Format Convertly’s Quality guides for topics like whether conversion reduces quality, JPG↔PNG myths, WebP/MP3/MP4 tradeoffs, recovery limits, and generational loss — each links to the right converter.
What is a MP4 file?
MP4 is a ubiquitous multimedia container usually holding H.264/H.265 video and AAC audio. MP4 is the safest video delivery format for phones, web, and social platforms. Shoot or edit in whatever your camera prefers, then provide an MP4 derivative for sharing.
Is MP4 lossy or lossless?
MP4 is typically lossy (lossy (codec-dependent)). That keeps files small but means discarded detail cannot be restored later.
What is a FLV file?
FLV is Flash Video — a legacy streaming format from the Adobe Flash era. FLV powered early YouTube-style streaming inside Flash Player. Flash is gone — convert FLV to MP4 to keep old recordings playable on modern devices.
Is MP4 to FLV private?
Yes. The file is processed locally in your browser and is not uploaded to Format Convertly servers.
Ready to Convert Your Files?
MP4 to FLV privately in your browser.