Quick answer: To send a large MKV file, upload it to Share Large Video Files (up to 20 GB, no account) and share the download link: the file arrives unchanged. A 1-hour 1080p screen recording is about 3.9 GB, more than most email providers accept.
What is a MKV file?
MKV (Matroska) is an open container that can hold almost any video codec together with several audio tracks, subtitle tracks and chapter markers in one file. That flexibility makes it popular for screen recordings from OBS Studio, for archiving films with multiple languages and for gaming footage.
MKV files can be huge because the container does not limit what goes in. A lossless remux of a Blu-ray keeps the original high-bitrate video and audio untouched, and OBS recordings at high quality settings grow by hundreds of MB every few minutes.
Extensions: .mkv, .mka, .mks.
How big are MKV files?
| File | Typical size |
|---|---|
| 1 hour of 1080p 60 fps OBS gameplay recording | roughly 5 to 20 GB, depending on the bitrate you set |
| A 2-hour film at 1080p with typical streaming-level quality | roughly 2 to 8 GB |
| A full Blu-ray remux of a feature film | roughly 20 to 40 GB |
| A 30-minute 1080p lecture or meeting recording | roughly 300 MB to 1.5 GB |
Which apps can send one?
Can you send a 1-hour 1080p screen recording (about 3.9 GB) as an attachment?
| App | Limit | Fits? |
|---|---|---|
| Gmail | 25 MB per email | No, send a link |
| Outlook.com | 20 to 25 MB per email | No, send a link |
| WhatsApp (document) | 2 GB per file | No, send a link |
| Telegram | 2 GB per file | No, send a link |
| Facebook Messenger | 100 MB per file | No, send a link |
| Discord (free) | 20 MB per file | No, send a link |
| Slack | 1 GB per file | No, send a link |
| WeTransfer (free) | 3 GB per transfer | No, send a link |
| Share Large Video Files | 20 GB per transfer | Send the link anywhere |
Limits from our file size limits by app table, checked against each service's help pages.
How to send MKV files without changing them
- Open Share Large Video Files in any browser and choose Get a link (or Send by email).
- Drop MKV files on the upload box, or pick a whole folder. Up to 20 GB and 1000 files per transfer.
- Optional: add a password, a download limit or an expiry under More options.
- Copy the link (or show the QR code) and send it by chat or email. The recipient downloads the original file, byte for byte.
Tips for sending MKV files
- Tell the recipient to use VLC if they are on a Mac, because QuickTime will not open MKV.
- Subtitles and extra audio tracks live inside the MKV, so there is no need to send them separately.
- If you recorded with OBS, let the recording finish cleanly before sending; a crashed recording may be unreadable, and MKV is more forgiving than MP4 in that case.
- Convert to MP4 only if the recipient must edit it in software that does not accept MKV.
How to open a MKV file
VLC plays MKV on Windows, Mac, iPhone and Android, and is the safest thing to recommend. Recent versions of the Windows Media Player app also play many MKV files. On a Mac, QuickTime Player does not open MKV, so use VLC or IINA. On Android, VLC or MX Player work well.
On our download page: the recipient can watch an MKV before downloading it, because a playable MP4 copy is made for the page (the file they download is still your original MKV). To keep the subtitles as separate files, save them as SRT first with the free subtitle extractor.
Frequently asked questions
Can I open an MKV file on a Mac or iPhone?
Yes, with VLC, which is free on both. Apple's own QuickTime Player and Photos app do not support MKV.
Why does OBS record to MKV instead of MP4?
Because an MKV recording can still be read if OBS or the computer crashes mid-recording, while an unfinished MP4 is often lost. OBS can remux the MKV to MP4 afterwards without re-encoding.
Is converting MKV to MP4 lossless?
It can be. If the video and audio codecs are MP4-compatible (such as H.264 and AAC), a remux just copies the streams into a new container. If they are not, the video must be re-encoded, which can reduce quality.
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