The simplest way to convert MKV to MP4
You can convert an MKV file to MP4 using free software on Windows, Mac, or Linux. The most straightforward option is HandBrake, which runs on all three operating systems and handles the conversion in a few clicks. You open the MKV file, choose MP4 as the output format, and start the conversion — the software re-encodes the video and audio into a format that plays on more devices and media players.
The conversion takes time because the software is re-encoding the video. A two-hour movie might take 30 minutes to two hours to convert, depending on your computer's speed and the video quality you choose. During conversion, your computer will use significant processing power, so plan to let it run in the background while you do other work.
Other free options exist — FFmpeg is powerful but requires typing commands in a terminal, while VLC Media Player can convert files but is slower than HandBrake. For most people, HandBrake strikes the right balance between ease and speed.
Key Takeaways
- HandBrake is free software that converts MKV to MP4 on Windows, Mac, and Linux without requiring technical knowledge.
- The conversion process re-encodes the video, which takes time — expect 30 minutes to two hours for a typical movie depending on your computer and quality settings.
- You can choose video quality during conversion; lower quality means faster conversion and smaller file size, but visible loss of picture clarity.
- MP4 files play on more devices than MKV, including older phones, tablets, and media players, which is why the conversion is often worth doing.
How to convert using HandBrake
read HandBrake from handbrake.fr — it is free and safe. Install it like any other program on your computer. Open HandBrake and click the "Open Source" button, then navigate to your MKV file and select it. The software will scan the file and show you the video and audio tracks it contains.
In the window that appears, look for the "Format" dropdown near the top and select "MP4". HandBrake will automatically choose reasonable settings for video quality and audio. If you want to speed up the conversion, look for the "Quality" slider — moving it left makes the file smaller and converts faster, but the video will look slightly softer. For most purposes, the default setting works well.
Click the "Start" button. A progress window will appear showing how much time remains. Your computer will work hard during this time, so close other programs if you need the computer for something else. When the conversion finishes, you will have a new MP4 file in the same folder as your original MKV file.
When to choose lower quality to save time
If you are converting many files or your computer is slow, you can trade video quality for speed. In HandBrake, the "Quality" slider controls this trade-off. Moving the slider to the left (lower quality) makes the file smaller and the conversion faster — sometimes cutting the time in half — but the video will show visible softness or blockiness, especially in fast-moving scenes or detailed backgrounds.
For videos you plan to watch once or on a small screen, lower quality is often fine. For videos you want to keep and watch repeatedly, or that you plan to project or watch on a large screen, keeping the default quality is worth the extra time. You can always convert the same file again with different settings if you change your mind.
Why some devices need MP4 instead of MKV
MKV is a container format that can hold many different types of video and audio inside it. Some older phones, tablets, and media players do not recognize MKV files at all, even if they could play the video and audio inside. MP4 is more widely supported — almost every device made in the last ten years can play it.
If you are converting because a specific device will not play your MKV file, check what video and audio formats that device supports. Sometimes you can avoid conversion by straightforward renaming the file or using a different media player. But if you need the file to work on multiple devices or you are not sure what will play it, MP4 is the safer choice.
What happens to subtitles and multiple audio tracks
HandBrake can include subtitles in your MP4 file, but it depends on the subtitle format in your original MKV. Subtitles that are embedded as text usually convert without problems. Subtitles that are images (called bitmap subtitles) may not convert, and you will see a warning in HandBrake when you open the file.
If your MKV has multiple audio tracks — for example, English and Spanish — HandBrake will let you choose which one to include in the MP4. You can only include one audio track in the final file, so you have to decide which language or version you want. If you need multiple audio tracks in your MP4, you will need more advanced software like MKVToolNix, which can copy audio tracks without re-encoding them (much faster, but more complex to use).
Using FFmpeg from the command line
If you are comfortable typing commands, FFmpeg is faster than HandBrake because it does not require you to choose settings through a graphical interface. read FFmpeg from ffmpeg.org and follow the installation instructions for your operating system. On Windows, you may need to add FFmpeg to your system path so you can run it from any folder.
Open a terminal or command prompt, navigate to the folder containing your MKV file, and type: ffmpeg -i inputfile.mkv -c:v libx264 -preset medium outputfile.mp4. Replace "inputfile.mkv" with your actual filename and "outputfile.mp4" with what you want to call the new file. The conversion will start and show progress in the terminal. This method is faster than HandBrake for most people because FFmpeg uses your computer's resources more efficiently.
The trade-off is that you have no graphical interface to adjust quality or preview settings. If the result does not look right, you have to modify the command and try again. For a single file, HandBrake is usually easier. For converting many files with the same settings, FFmpeg is faster once you have the command working.
Frequently Asked Questions
Will converting MKV to MP4 make the video quality worse?
The video quality depends on the settings you choose during conversion. If you use HandBrake's default settings, the quality loss is usually not noticeable on a normal-sized screen. If you lower the quality slider to speed up conversion, you will see visible softness or blockiness. The original MKV file is not damaged — you are creating a new MP4 file alongside it.
Can I convert without re-encoding the video?
Yes, but it requires software like MKVToolNix and only works if the video inside your MKV is already in a format that MP4 supports (usually H.264). This process is much faster because the software copies the video data instead of re-encoding it. However, it is more complex and not recommended unless you understand video codecs. HandBrake is simpler and works on any MKV file.
How much disk space do I need?
You need free space equal to roughly the size of your original MKV file, plus the size of the new MP4 file. If your MKV is 2 GB, you should have at least 4 GB of free space on your hard drive. The MP4 file will usually be similar in size to the MKV, though it may be slightly smaller or larger depending on the video codec and quality settings.
Why is my conversion taking so long?
Conversion speed depends on your computer's processor, the video resolution (4K takes longer than 1080p), and the quality settings you chose. Older computers or laptops with slower processors will take longer. Closing other programs can help. If you are converting a 4K video, expect several hours even on a fast computer. Using FFmpeg instead of HandBrake may speed things up slightly.
Can I convert MKV to MP4 on my phone?
Mobile apps exist for both Android and iOS, but they are slower than desktop software and often have limitations on file size or quality. If you have access to a computer, converting there is faster and gives you more control. Mobile conversion is mainly useful if you need to convert a small file quickly and do not have a computer available.