Convert MKV to FLV Online Free

Convert Matroska MKV video files to FLV for Flash-compatible players and legacy streaming platforms. ChangeThisFile uses FFmpeg on secure servers — no installation or signup needed.

By ChangeThisFile Team · Last updated: March 2026

Quick Answer

ChangeThisFile converts Matroska to FLV using FFmpeg, a professional-grade multimedia framework, to transcode Matroska files to FLV format with optimized codec settings and quality preservation. Free with no signup required. Files are encrypted during transfer and automatically deleted from our servers after conversion.

Free No signup required Encrypted transfer · Auto-deleted Under 2 minutes Updated March 2026

Convert Matroska to FLV

Drop your Matroska file here to convert it instantly

Drag & drop your .mkv file here, or click to browse

Convert to FLV instantly

Matroska vs FLV: Format Comparison

Key differences between the two formats

Feature	MKV (Matroska)	FLV
Full Name	Matroska Video	Flash Video
Developer	Matroska.org	Adobe Systems
Open Standard	Yes	No (proprietary)
Video Codec	H.264, H.265, VP9, AV1, MPEG-4	H.263, VP6, H.264
Audio Codec	AAC, FLAC, AC-3, MP3, Vorbis	MP3, AAC, Nellymoser
Subtitle Tracks	Multiple formats supported	Not natively supported
Browser Support	Via HTML5 with plugin	Requires Flash Player
Streaming	HTTP, HLS, DASH	RTMP

When to Convert

Common scenarios where this conversion is useful

Flash Platform Submissions

Convert MKV content for upload to legacy Flash-based video platforms, portals, or CMS systems that require FLV input format.

RTMP Streaming Archives

Prepare MKV media files as FLV for ingestion into RTMP-based streaming servers and legacy broadcast workflows.

Consistent Legacy Format Libraries

Convert MKV files to FLV to maintain a uniform format across existing Flash-era video archives and libraries.

Older Embedded Video Players

Supply FLV content for Flash-based video players embedded in legacy websites or enterprise intranets.

E-Learning Flash Platforms

Convert MKV training videos to FLV for upload to e-learning systems built on Adobe Flash-based video delivery.

Who Uses This Conversion

Tailored guidance for different workflows

Content Creators

Convert Matroska footage to FLV for uploading to YouTube, TikTok, or social media platforms
Transform Matroska screen recordings to FLV for sharing in blog posts or tutorials

Choose FLV at 1080p or higher for the best quality-to-size ratio on social platforms

Preview the converted FLV file before uploading to ensure audio sync is maintained

Video Editors

Convert Matroska raw footage to FLV for importing into editing software like Premiere or DaVinci Resolve
Transform Matroska project exports to FLV for client delivery or final distribution

Maintain the original resolution and frame rate during Matroska to FLV conversion to avoid quality loss

Use a high bitrate when converting to FLV if the footage will undergo further editing

Social Media Managers

Convert Matroska brand videos to FLV to meet platform-specific format requirements
Transform Matroska ad creatives to FLV for cross-platform publishing campaigns

Check each platform's recommended FLV specs (resolution, bitrate, duration) before uploading

Keep the Matroska original archived for future re-exports at different resolutions

How to Convert Matroska to FLV

1

Upload Your MKV File

Click or drag to upload your Matroska MKV file. The upload is secured with HTTPS encryption to protect your content in transit.
2

FFmpeg Converts to FLV

Our servers use FFmpeg to encode your MKV content into an FLV container with H.264 video and AAC audio for Flash-compatible playback.
3

Download Your FLV

Download the finished FLV when conversion completes. Your original MKV file is permanently deleted from our servers immediately after.

Frequently Asked Questions

Why convert MKV to FLV?

FLV is required for legacy Flash-based video platforms, RTMP streaming servers, and older video players that predate H.264 MP4 support. While Flash is deprecated, FLV archives and some platforms still require this format.

Can I play FLV without Adobe Flash Player?

Yes. VLC, MPC-HC, and other modern media players support FLV playback without requiring Flash Player. Flash Player itself was discontinued by Adobe in 2020.

Does FLV support the subtitles in my MKV file?

No. FLV does not support embedded subtitle tracks. You will need to burn subtitles into the video or manage them as separate files.

Will all MKV audio tracks convert to FLV?

Only the primary audio track is converted to the FLV container. Multiple audio tracks in MKV are not supported in FLV format.

What happens to my file after conversion?

Both your uploaded MKV and the converted FLV are deleted from our servers automatically after your download completes.

How large can my MKV file be?

Files up to 25MB (free tier; 500MB on Pro) are supported. For larger MKV files, compress or trim the video beforehand.

Does FLV support HD resolution?

Yes, FLV with H.264 encoding supports 720p and 1080p HD resolutions. The output maintains your source MKV resolution.

Is this free?

Yes, completely free. ChangeThisFile requires no payment, no account, and adds no watermarks.

What codec does the FLV output use?

The converted FLV uses H.264 video encoding with AAC audio, providing the best quality-to-size ratio for Flash-compatible delivery.

Can I convert MKV files with multiple video tracks?

Only the primary video track is processed. MKV's multiple-track capability is not carried over to the FLV container.

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Need to convert programmatically?

Use the ChangeThisFile API to convert Matroska to FLV in your app. No rate limits, up to 500MB files, simple REST endpoint.

View API Docs

Read our guides on file formats and conversion

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