The MKV format gives you powerful options.
But figuring out how to actually add those subtitles — without re-encoding your video or using overly complex software — can be confusing.
In this guide, we'll break down the difference between soft and hard subtitles for MKV files and show you exactly how to add each type.
If you're working with MKV files and wondering what kind of subtitles they can support — the answer is: both. One of the biggest strengths of the MKV (Matroska Video) format is its flexibility when it comes to handling subtitles.
Soft subtitles are text-based subtitle tracks that are included inside the MKV container, but they’re not part of the actual video image. Instead, they’re stored as a separate track — just like audio or metadata — and most video players (like VLC, MPC-HC, or Kodi) will recognize them.
When you open an MKV file with soft subtitles, you’ll usually see them listed in the subtitle menu of your player. You can:
MKV files can support multiple subtitle formats, including:
Because they’re stored inside the file but remain editable and removable, soft subtitles are ideal when you want flexibility, language options, or accessibility settings.
Hardcoded subtitles, on the other hand, are burned directly into the video. .
These subtitles aren’t a separate track — they’re part of the image itself. If your MKV video has hardcoded subtitles, they’ll display no matter where or how you play the file.
If you want to add toggleable subtitles to your MKV video — the kind viewers can turn on or off in VLC or another player — then you’re looking to add soft subtitles. The good news is: you can do this easily and without re-encoding your entire video.
Here’s how to do it using a free tool called MKVToolNix.
Head over to mkvtoolnix.download and install MKVToolNix GUI on your computer. It’s available for Windows, macOS, and Linux.
This tool lets you add subtitle tracks to your MKV video without affecting the original video or audio quality.
Launch MKVToolNix and drag your MKV video file into the window — or click “Add source files” and choose your video manually.
You’ll now see all the video and audio tracks listed. This is where you manage what goes in the final MKV output.
Next, drag your SRT, ASS, or VTT subtitle file into the window — or click “Add source files” again and select it.
Once imported, the subtitle file will appear as a new track. Make sure the checkbox next to it is ticked — that means it will be included in your final file.
You can also:
At the bottom of the window, you’ll see an output file path. Choose where you want to save your new MKV file.
Click “Start Multiplexing.” This process usually takes just a few seconds and won’t re-encode your video — so there’s no loss in quality.
Once it’s done, you’ll have a new MKV file with embedded soft subtitles.
Open the new MKV file in VLC, Media Player Classic, or any player that supports subtitle tracks. You should see the subtitles listed under the subtitle menu. You can toggle them on or off — or switch between multiple tracks if you’ve added more than one.
If you want your subtitles to always appear on screen, no matter what player is used, you’ll need to burn them directly into your MKV video. This process is called hardcoding, and it’s perfect for content where you don’t want viewers to toggle captions on or off — like tutorials, social media clips, or multilingual videos without native audio.
Unlike soft subtitles, hard subtitles become part of the video image itself. And once they’re there, they can’t be turned off or edited — so make sure your timing and text are spot on before exporting.
Let’s look at how to do this step by step using HandBrake and an external subtitle generator like Checksub.
Step 1: Prepare Your Subtitle File
Before you burn subtitles into your MKV file, you’ll need a subtitle file — usually in SRT or ASS format.
You can create one manually, or use a tool like Checksub to generate accurate subtitles automatically (more on that in the next section). Make sure your file is synced with the audio in your video.
Step 2: Open Your MKV File in HandBrake
Download and install HandBrake (free and open-source) from handbrake.fr.
Once installed, launch the app and drag your MKV video into the main window. HandBrake will scan the video and open up its settings.
Step 3: Add and Burn the Subtitles
Go to the “Subtitles” tab in HandBrake.
Click “Import Subtitle” and select your SRT or ASS file. If you’re working with styled subtitles (ASS format), HandBrake will preserve font and positioning — to a degree.
Now check the “Burn In” box next to the subtitle track. This tells HandBrake to embed the subtitles directly into the video image.
You can also adjust subtitle delay or force the subtitles if needed, but for most cases, the default settings will do the trick.
Step 4: Choose Output Settings and Start Encoding
Pick your desired export format — we recommend sticking with MKV for consistency.
Click “Browse” to choose where to save the new file, then hit “Start Encode.” HandBrake will begin rendering your new MKV video with hardcoded subtitles.
Depending on your system and video length, this could take a few minutes.
Manually writing subtitles, syncing them, and exporting them in the right format can be time-consuming — especially if you’re working with longer videos or multiple languages. That’s exactly where Checksub comes in.
Start by going to checksub.com and logging into your account. Don’t have one? Signing up is quick and free to try.
Once inside, click on “Upload Video” and choose your MKV file. Checksub accepts most major formats, so you won’t need to convert your video beforehand.
Now select the original language of your video. If you want subtitles in more than one language, Checksub also offers automatic translation in over 267 languages.
After upload, Checksub’s AI will start analyzing your video. Within minutes, it will:
Inside Checksub’s editor, you can:
When your subtitles are ready, click “Export” and choose how you want to use them:
You can also download both if you want flexibility for different platforms.
Want to add subtitles to your MKV files in one click ? Try Checksub for free now.
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