01
Right-sized output for the use case
Converting from FLV to MKV aligns the file with the encoding choices the downstream pipeline expects. The result is a deliverable that fits naturally into the destination workflow.
100% local
VIDEO
Convert FLV
to MKV
Right-sized output for the use case.
Converting from FLV to MKV aligns the file with the encoding choices the downstream pipeline expects. The result is a deliverable that fits naturally into the destination workflow.
— Drop area
WHY CONVERT
Why convert FLV to MKV
02
Broader cross-platform support
MKV is accepted by a wider range of video players, mobile devices, and streaming platforms than FLV. The conversion removes a recurring compatibility friction without changing what the file actually contains.
03
Lower storage and bandwidth cost
MKV files are typically smaller than their FLV counterparts, which reduces hosting, transfer, and storage costs at scale. The savings compound when serving the same content to many recipients.
— How to convert
FLV to MKV in three steps.
- 01
Open LocalConvert
Visit this page on any modern browser — no install, no signup, no plugin.
- 02
Drop or select your FLV file
Drag your FLV into the drop area, or click to pick one from your device.
- 03
Click Convert
Conversion runs entirely in your browser. When it's done, your MKV file downloads to your device.
QUALITY & FIDELITY
Quality and fidelity
- Lossy source to lossless target: existing artifacts are preserved but no new loss is added.
- Metadata (EXIF/tags) is preserved where the source provides it.
Transparency FLV
✗ MKV
✗
Color depth 8-bit video, MP3/AAC audio any (container)
Metadata preserved ✓
FORMAT SPECS
Format specifications
| FLV | MKV | |
|---|---|---|
| Extensions | .flv | .mkv .mka .mks |
| MIME types | video/x-flv | video/x-matroska |
| Introduced | 2002 | 2002 |
| Maintainer | Adobe | Matroska / CELLAR (IETF) |
| Magic # | 46 4C 56 | 1A 45 DF A3 |
| Spec | View spec ↗ | View spec ↗ |
COMPATIBILITY
Where these formats work
| Platform | Windows | macOS | iOS | Android | Chrome | Firefox | Safari | Edge |
|---|---|---|---|---|---|---|---|---|
| FLV | App | App | App | App | — | — | — | — |
| MKV | Native | App | App | App | — | — | — | — |
FLV
- Windows
- App
- macOS
- App
- iOS
- App
- Android
- App
- Chrome
- —
- Firefox
- —
- Safari
- —
- Edge
- —
MKV
- Windows
- Native
- macOS
- App
- iOS
- App
- Android
- App
- Chrome
- —
- Firefox
- —
- Safari
- —
- Edge
- —
Why LocalConvert
How LocalConvert compares
| Category | LocalConvert | Cloud converters |
|---|---|---|
| PRIVACY | Files never leave your device. The whole pipeline runs in your browser via WebAssembly. | Files travel to a remote server, sit in queue storage, and may be retained for analytics or moderation. |
| COST | Free, no signup, no daily quotas. | Often free for small files; paid tiers for batch / large / commercial use. |
| LIMITS | Limited only by your device's memory and CPU. Multi-GB raw footage OK on desktop. | Typical 100 MB to 1 GB per-file caps, plus rate limits. |
— The formats
From · FLV
Flash Video
A legacy Flash-era container largely replaced by MP4 and WebM.
Typical uses
Legacy web video, archived Flash content.
To · MKV
Matroska Video
An open, flexible container that can hold virtually any video, audio, and subtitle codec.
Typical uses
Movie archives, multi-language releases, home media.
— FAQ
Frequently asked.
Is FLV to MKV conversion free?
Yes. LocalConvert is completely free, with no signup and no per-file or per-day limits.
Do my files get uploaded anywhere?
No. FLV to MKV conversion happens entirely inside your browser using WebAssembly — your file never leaves your device.
What's the maximum file size?
There's no fixed cap — the practical limit is your device's available memory. Very large files may take longer or fail on low-RAM devices.
Does it work offline?
Yes — once the page has loaded, FLV to MKV conversion works without an internet connection. Re-open the page once to cache it.
Will conversion preserve quality?
LocalConvert uses the industry-standard tools (FFmpeg, ImageMagick, Pandoc) — quality matches what professionals use on the command line. Lossy formats will still lose some quality on each re-encode.
— Related
Or convert these.
Browse all conversionsREFERENCES
Format references
Last verified:
100% local conversion.
FLV to MKV is processed in your browser with WebAssembly. No upload, no tracking, no limits. Your file never leaves your device.