FLV vs MP4: Which Should You Use?

Side-by-side comparison of FLV and MP4 video formats — features, pros, cons, and conversion options.

Quick Answer

FLV is best for Legacy Flash-based web video (largely obsolete). MP4 is best for Video distribution, streaming, and sharing.

Quick Verdict

FLV Best for Legacy Flash-based web video (largely obsolete)

✓ Small file size
✓ Fast loading
✓ Flash Player legacy support
✗ Flash is deprecated

Convert FLV to MP4 →

MP4 Best for Video distribution, streaming, and sharing

✓ Universal compatibility
✓ Excellent compression
✓ Streaming-optimized
✗ Patent-encumbered codecs (H.264/H.265)

Convert MP4 to FLV →

Specs Comparison

Side-by-side technical comparison of FLV and MP4

Feature	FLV	MP4
Category	Video	Video
Year Introduced	2003	2001
MIME Type	video/x-flv	video/mp4
Extensions	.flv	.mp4, .m4v
Container	✓	✓
Codecs	H.264,VP6,Sorenson Spark	H.264,H.265,VP9,AV1,AAC
Max Resolution	1080p	8K
Streaming	✓	✓
Subtitle Support	✗	✓

Pros & Cons

FLV

Pros

✓ Small file size
✓ Fast loading
✓ Flash Player legacy support

Cons

✗ Flash is deprecated
✗ Poor mobile support
✗ Limited modern use

MP4

Pros

✓ Universal compatibility
✓ Excellent compression
✓ Streaming-optimized

Cons

✗ Patent-encumbered codecs (H.264/H.265)
✗ Not ideal for editing
✗ DRM can limit playback

When to Use Each

Choose FLV when...

You need files optimized for Legacy Flash-based web video (largely obsolete)
Small file size
Fast loading

Choose MP4 when...

You need files optimized for Video distribution, streaming, and sharing
Universal compatibility
Excellent compression

How to Convert

Convert between FLV and MP4 for free on ChangeThisFile

Convert FLV to MP4 Server-side conversion — auto-deleted after processing Convert MP4 to FLV Server-side conversion — auto-deleted after processing

Frequently Asked Questions

What's the difference between FLV and MP4?

FLV is best for Legacy Flash-based web video (largely obsolete), while MP4 is best for Video distribution, streaming, and sharing. Both are video formats but they differ in compression, compatibility, and intended use cases.

Is FLV or MP4 better for video?

It depends on your use case. FLV is better for Legacy Flash-based web video (largely obsolete). MP4 is better for Video distribution, streaming, and sharing. Consider your specific requirements when choosing between them.

How do I convert FLV to MP4?

Go to the FLV to MP4 converter on ChangeThisFile. Upload your file and the conversion processes on the server, then auto-deletes. It's free with no signup required.

Can I convert MP4 to FLV?

Yes. ChangeThisFile supports MP4 to FLV conversion. Upload your file for server-side conversion — files are auto-deleted after processing.

Which is smaller, FLV or MP4?

File size varies depending on the content, compression method, and quality settings of each format. In general, lossy formats produce smaller files than lossless ones. Test with your specific files to compare actual sizes.

Does FLV support subtitle support?

No, FLV does not support subtitle support, whereas MP4 does. This may be an important factor depending on your use case.

Is FLV or MP4 free to use?

Both FLV and MP4 are supported file formats that are free to use. You can convert between them for free on ChangeThisFile — server-side conversions are free with no signup required.

Which format is newer, FLV or MP4?

FLV is newer — it was introduced in 2003, while MP4 dates back to 2001. Newer formats often offer better compression and features, but older formats tend to have wider compatibility.