Convert FLV to MKV
Free online FLV to MKV converter. No signup required.
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Max file size: 100 MB
When to convert FLV to MKV
Use this conversion when your destination needs MKV and you have a FLV source. Keep the original so you can compare the result or try another supported format.
Video is re-encoded using the selected output’s defaults. Image quality, audio and metadata can change. Check playback and duration in the application where you will use it.
FLV vs MKV: Format Comparison
Side-by-side comparison of the source and target formats.
| Property | FLV (Source) | MKV (Target) |
|---|---|---|
| Extension | .flv | .mkv |
| Full Name | Flash Video | Matroska Video |
| Compression | Lossy | Lossy |
| File Size | Varies | Medium |
| Best For | Legacy web video archives and content migration | High-definition movie and TV show storage wit… |
| Browser Support | Limited | Wide |
How to Convert FLV to MKV
Follow these simple steps to convert your file in seconds.
Choose a FLV file
Select or drop one file up to 100 MB. Its extension must match this converter. Availability is checked before transfer.
Convert to MKV
Video is re-encoded using the selected output’s defaults. Image quality, audio and metadata can change. Check playback and duration in the application where you will use it.
Download and check the result
Use Download after conversion completes. Open the result and check its content, quality and formatting before sharing it. Download links expire one hour after upload finishes. Uploaded and converted files are removed automatically by regular cleanup. Files may become unavailable sooner when the service restarts.
Tips for Converting FLV to MKV
Practical advice to get the best results from this conversion.
Why this conversion is worth doing
Flash Video has a known limitation: obsolete format since Adobe Flash Player reached end-of-life in 2020. Matroska Video addresses this with a key advantage: supports virtually any codec and unlimited tracks for audio, subtitles, and video. Converting from FLV to MKV is most worthwhile when this specific trade-off matters for the way you intend to use the file.
Match the format to the actual workflow
Flash Video is most commonly used for legacy web video archives and content migration, while Matroska Video is the standard for high-definition movie and tv show storage with multiple audio and subtitle tracks. If your workflow is closer to the second pattern, converting makes sense. If you are still working in a context where FLV is the norm, converting may create unnecessary compatibility friction with collaborators or tools that expect the source format.
Watch for this limitation in the MKV output
Matroska Video has its own limitation worth understanding before you commit: not natively supported by all hardware devices and smart TVs. After the conversion completes, open the MKV file and verify that this limitation does not affect your specific use case — for some workflows it is irrelevant; for others it can be a deal-breaker.
Avoid transcoding unless necessary
Every time you transcode (re-encode) a video, some quality is lost unless you use a lossless codec. If you only need to change the container format without changing the codec, use a remux (stream copy) operation instead of a full re-encode. This preserves original quality and is much faster.
Understanding FLV and MKV Formats
Learn about the source and target file formats to understand what happens during conversion.
Source Format
Flash Video
video/x-flvFLV (Flash Video) is a container format that was used to deliver video content over the internet via Adobe Flash Player. It typically contains video encoded with Sorenson Spark or VP6 codecs and audio in MP3 or AAC format. FLV was once the dominant web video format but became obsolete after major browsers discontinued Flash Player support in 2020.
Advantages
- Compact file sizes with acceptable streaming quality
- Simple container structure that is quick to parse
- Large existing archive of legacy web video content
Limitations
- Obsolete format since Adobe Flash Player reached end-of-life in 2020
- No modern browser supports FLV playback without third-party tools
- Limited codec support compared to modern containers like MP4
Common Uses
- Legacy web video archives and content migration
- Converting old Flash-based video content to modern formats
- Historical video content from early streaming platforms
Target Format
Matroska Video
video/x-matroskaMKV (Matroska Video) is a free, open-standard multimedia container that can hold an unlimited number of video, audio, subtitle, and metadata tracks in a single file. It supports virtually any codec and is especially popular for high-definition video content with multiple audio and subtitle options. Matroska is designed to be future-proof with a flexible, extensible EBML-based structure.
Advantages
- Supports virtually any codec and unlimited tracks for audio, subtitles, and video
- Rich feature set including chapters, menus, metadata, and attachments
- Open standard that is free and widely supported by media players
Limitations
- Not natively supported by all hardware devices and smart TVs
- Larger overhead compared to simpler containers like MP4
- Not supported for direct playback in most web browsers
Common Uses
- High-definition movie and TV show storage with multiple audio and subtitle tracks
- Anime and media collections requiring multiple language options
- Video archival with comprehensive metadata preservation
Frequently Asked Questions
Common questions about converting FLV to MKV.
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