Contents

Part 1. What’s the Difference Between MKV and MP4
Part 2. Convert/Remux MKV to MP4 with Aiseesoft [Fastest Batch Conversion]
1. Aiseesoft Video Converter Ultimate
Part 3. Convert with Free & Open-source Tools
Part 4. The Free Online Way: For Small Files (Online Tools)
Part 5. FAQs of Converting MKV to MP4

How to Convert MKV to MP4 with Lossless Quality and Super Fast Speed

February 28, 2026Jenny Ryan

As an open-standard container, MKV (Matroska) is a favorite for cinephiles because it supports multiple audio tracks and subtitles without compromising quality. However, this complexity often leads to compatibility issues with standard media players, editing software, and mobile ecosystems.

To ensure seamless playback, there is a massive demand to convert MKV to MP4, the universal standard. Whether you need to upload videos to the web, edit in Professional suites on PC/Mac, or enjoy movies on iPhone, Android, or tablets, switching to MP4 provides the perfect balance of high quality and broad accessibility.

Converter	Best For	Speed	Quality	Batch Mode	Key Benefit
Aiseesoft Video Converter Ultimate	Pro Users: Lossless, Ultra-fast, Large Batch Tasks	120X (Lightning)	Lossless (Remux)	Yes (Robust)	One-click solution for 4K/8K batch conversion.
Handbrake	Tech-savvy users who need deep open-source encoding.	Moderate	High	Yes	Totally free; allows detailed parameter tuning.
VLC Media Player	Quick, one-off conversions for users who already have it.	Slow	Average	No	No installation required if you already use it to play videos.
FFmpeg	Advanced users who want full control and automation	Very fast	High	Yes	Maximum control, automation, and zero-loss remuxing
Shutter Encoder	Users who want lossless conversion with a GUI	Fast	High	Yes	Simplifies tasks with an intuitive visual workflow
Aiseesoft Free Video Converter Online	Users needing a fast, web-based tool for medium files.	High (Web)	High	Limited	Safe, clean, and supports larger files than most web tools.
CloudConvert	Users converting small files directly from Google Drive.	Server-based	Variable	Limited	Excellent cloud integration; no CPU usage on your PC.
Convertio	Occasional users with very small files (<100MB).	Moderate	Standard	No	Supports a huge variety of rare file formats.
FreeConvert	Users looking for high free file size limits online.	Slow	Standard	Limited	Supports files up to 1GB for free, but with heavy ads.

Part 1. What’s the Difference Between MKV and MP4

When converting video files into other formats, it is useful to know about the formats. Multiple audio tracks, subtitles, or even chapters can be included in a single file using the MKV (Matroska Video) container format. MKV is decent at preserving video quality. However, support is limited on most devices or media players, especially on Macs, and in mobile applications. On the other hand, MP4 (MPEG-4 Part 14) is one of the most common and recognized video formats. MP4 is highly compatible with most devices, media players, and online services. An MP4 file is typically smaller than an MKV file and maintains very good video quality. MP4 files are also helpful for sharing or streaming video.

Key Differences

Feature	MKV	MP4
Compatibility	Limited on some devices	Widely supported
File Size	Larger, high-quality	Smaller, efficient
Features	Supports multiple audio, subtitles, and chapters	Basic single audio & subtitles
Best For	High-quality storage, backup	Streaming, sharing, device playback

Understanding these differences helps you decide why converting MKV to MP4 is often necessary, especially for smooth playback on Mac, iPhone, or other devices.

Part 2. Convert/Remux MKV to MP4 with Aiseesoft [Fastest Batch Conversion]

Aiseesoft Video Converter Ultimate

If you need a solution that balances lightning speed with cinematic quality, Aiseesoft Video Converter Ultimate is the industry standard. Unlike basic tools that often crash or degrade your footage, this software is engineered to handle massive 4K/8K MKV libraries with ease. Besides the main feature that helps you convert video formats, this software offers additional functions. For example, you can trim/crop your videos after converting from MKV to MP4. And it lets you enhance video effects.

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Steps to convert or remux MKV to MP4 with Aiseesoft Video Converter Ultimate:

Step 1.

Install MKV to MP4 Converter on your computer and click “Add File" under “Video Converter” to upload the MKV file you want to convert. You can also select multiple videos to import.

Step 2.

Click “Output Format” to select MP4 as your destination format.

Step 3.

You can click “Settings” to edit the profile, like video quality, encoder, sample rate, etc. If you want a higher speed, you can enable “Hardware acceleration”. Then, you can click “Convert All” to change MKV into MP4.

Step 4.

If you want to remux the MKV to MP4 without compression and quality loss, you just need to enable “120× Faster Conversion”, which only swaps the MKV container to MP4 without really encoding the video stream.

Just a few seconds later, the original MKV videos will be converted to MP4 files. Many people may pay more attention to video quality after the MKV-to-MP4 conversion. Here, the best MKV to MP4 conversion software promises you can convert MKV to MP4 without losing any quality. In addition, the conversion speed is super-fast - beyond your imagination.

Part 3. Convert with Free & Open-source Tools

HandBrake

HandBrake is a professional-grade transcoder. It is best when you want to compress a file or ensure compatibility with specific devices like an iPhone or Apple TV. It’d be better if you have a huge 4K MKV file and you want to shrink it down to a smaller MP4 for your phone without it looking blurry.

Steps to transform MKV to MP4 with HandBrake:

Step 1.

Drag your MKV file into HandBrake.

Step 2.

Choose a preset (e.g., "Very Fast 1080p30") from the right panel.

Step 3.

Set the format as “MP4” in the “Summary” tab. Note that you also need to manually change the file extension in the “Save As” tab to “MP4.

Step 4.

Click “Start Encode”.

HandBrake always re-encodes the video. This means it will take more time and use more CPU, but it allows for better compression and fixed frame rates.

VLC Media Player

Most people already have VLC installed. It is great for a fast "remux" or a quick conversion without needing to learn new software. If you have a single file that just won't play on your TV and you need it converted in 60 seconds, you can give VLC a try.

Steps to turn MKV into MP4 using VLC:

Step 1.

Go to “Media” > “Convert / Save”.

Step 2.

Click “Add” to load your MKV files, then click “Convert / Save”.

Step 3.

Select “Video - H.264 + MP3 (MP4)” from the dropdown.

Step 4.

Click “Start” to transcode your MKV to MP4 video.

FFmpeg

FFmpeg is a free, open-source, command-line tool designed to handle multimedia files. It is considered the industry standard for video transcoding, remuxing, and streaming because it supports nearly every codec and format in existence. It is exceptionally fast when remuxing because it copies the original audio and video streams without re-encoding.

Steps to convert MKV to MP4 with FFmpeg (Remuxing with no quality loss):

Step 1.

Click the path of your MKV video and replace the path with CMD, then click the “Enter” button. Here, a command line will appear in Command Prompt.

Step 2.

Input this command line: ffmpeg – I “test.mkv” -c copy “test.mp4” (Please replace “test” with your file name.)

Step 3.

Click “Enter” to run the command. You will find an MP4 file appear in the same folder where your original MKV file exists.

Shutter Encoder

Shutter Encoder is a free, open-source converter designed for both video professionals and enthusiasts. Built on top of FFmpeg, it provides a user-friendly graphical interface for incredibly complex tasks. Its biggest strength is its ability to perform "Rewrapping" (Remuxing), which simply takes the video and audio streams out of the MKV container and puts them into an MP4 container without re-encoding the actual video data. This results in zero quality loss and extremely fast processing times.

Steps to change MKV to MP4 with Shutter Encoder:

Step 1.

Open Shutter Encoder.

Step 2.

Click “Browse” to select the MKV file manually or drag and drop your MKV file(s) into the drop zone.

Step 3.

Under the "Choose function" section, scroll down to select "Rewrap".

Step 4.

In the right-hand panel, set the extension to .mp4.

Step 5.

Click "Start function" at the bottom.

Part 4. The Free Online Way: For Small Files (Online Tools)

Aiseesoft Free Video Converter Online

Aiseesoft Free Video Converter Online is a free online tool that lets you quickly convert any video/audio to MOV, MP4, AVI, MKV, and more. With it, you can convert video files on most devices and social media. It also lets you adjust your video/audio bitrate, aspect ratio, resolution, and more. Here are some steps to convert MKV to MP4 using Video Converter Online.

Step 1.

Enter the official page of Aiseesoft Free Video Converter Online and click the “Add a File” button to import your MKV files.

Step 2.

After uploading your MKV file successfully, please select “MP4” on the right side of the interface and click the “Convert” button to start converting.

Step 3.

Wait for a while, your MKV file will be changed to MP4, and you can click the “Download” button to save the MP4 file to your computer.

CloudConvert

CloudConvert is a effective online tool for converting your videos. It supports MP4, MKV, WEBM, and AVI. With it, you can also adjust video resolution, file size, etc. Here are some steps to convert MKV to MP4 using CloudConvert.

Step 1.

Open the Cloudconvert website using your browser and click “Select File” in the middle of the interface to select your MKV file. Click the drop-down box on the top right to choose the MP4 format you want to output.

Step 2.

You can also click the drop-down box beside the settings icon to choose output format. Then, click “Convert”.

Convertio

Convertio is a free tool that lets you convert video and audio quickly. It supports most formats, including MP4, MKV, MOV, AVI, etc. You can use it as long as you have a browser. Here are the steps to convert MKV to MP4 using Convertio.

Step 1.

Open the Convertio website and click the red button in the main interface to select your MKV file.

Step 2.

Click the drop-down button to choose the output format as MP4.

Step 3.

Then, you can click “Convert” to get your MP4 file.

FreeConvert

FreeConvert is another online tool you can utilize to convert video. It is easy to use, just a few clicks, and you can convert your video successfully. It supports most media formats, including MP4, MKV, AVI, OGG, MP2, MID, and more. Here are some steps to convert MKV to MP4 using FreeConvert.

Step 1.

Click the “Choose Files” button in the middle of the page to upload your MKV file.

Step 2.

Select “MP4” as your output format from the box near the gear icon. Then, click the “Convert” button.

Part 5. FAQs of Converting MKV to MP4

Why is there no sound after converting MKV to MP4?

This usually happens due to an audio codec mismatch. MKV files often use DTS or AC3 audio, which some MP4 players don't support. To fix this, ensure your converter is set to convert audio to AAC or MP3, which are the most compatible formats for MP4 files.

Does converting MKV to MP4 lose quality?

Not if you use Remuxing (also known as "Stream Copy"). Since MKV and MP4 are just containers, tools like Aiseesoft Video Converter Ultimate can simply swap the container without re-encoding the video. If the software forces "Transcoding," you may see a slight dip in quality, but using a high-bitrate setting will make the difference nearly invisible.

Is MP4 better than MKV?

Considering compatibility, MP4 is widely supported for playing on most media players. MKV is more popular for converting Blu-ray and DVD files. For more comparison, you can check the video quality in MKV vs. MP4.

Conclusion

Converting MKV to MP4 doesn't have to be a choice between speed and quality. While free tools like VLC and HandBrake are great for occasional use, Aiseesoft Video Converter Ultimate provides the most reliable, lossless, and lightning-fast experience for batch tasks. Whether you're optimizing videos for your iPhone or clearing space on your hard drive, this all-in-one solution ensures a perfect result every time. Ready to save time? Download the free trial and experience 120× faster conversion today!

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