Best 3 Free MKV to MP4 Converter Online to Convert Big Files without Limit

Laura Goodwin Sep 18, 2021 Convert Video

MKV, as the advanced multimedia container, gains more popularity recently.

However, when it comes to the compatibility, MP4 gets more votes than MKV.

MKV is not accepted by a variety of players, mobile phones, and other devices, e.g. Avid Media Composer, etc.

As a result, the need of converting MKV to MP4 is increasing.

In this post, we gather the best 3 free MKV to MP4 converter online, and detailed steps to make the conversion.

Which one is the best one? You decide it after reading.

MKV to MP4 Converter Online

Part 1. Brief introduction of MKV VS MP4

What is MKV?

The extension of Matroska file is .mkv, which is the multimedia container, which hold video, audio, picture or subtitle in one file unlimitedly. MKV is always used to store multimedia content like movies or TV shows. Highly supporting H.264 and H.265, you could get a MKV file with high quality.

What is MP4?

MPEG-4 Part 14 or MP4, like MKV, is the digital multimedia container format to stored video, audio, subtitle and image. Allowing online playing, and high compression, MP4 is widely used in most devices.


Though MKV and MP4 are multimedia container, they work slightly differently.

As for the container format support by other software and players, MP4 is more widely supported and MKV may have a slight edge.

As far as the quality, both of them support HEVC (h.265) and h.264, so the output quality depends on your section of codec.

As file size, MKV is slight bigger than MP4 if other video or audio codec is the same.

So here, for getting a higher compatibility or smaller file size, MP4 is no doubt the better option.

Part 2. Top 3 free MKV to MP4 converter online

For converting MKV to MP4, there are massive desktop software can do it, VLC, Freemake Video Converter, Any Video Converter, HandBrake, etc.

However, we only focus on the free online MKV to MP4 converters today.

Here, we gather the best 3 MKV to MP4 converting programs to make the conversion.

Free Online Video Converter

Free Online Video Converter is the free online MKV to MP4 converting software with no limits of time or file size. Highly support over 1000 input formats, you could easily convert MKV to MP4, MOV, AVI, etc.

Convert.Files is an online based platform that you can use to make your file convert from MKV to MP4 with ease and convenience. It is the simple MKV to MP4 converter by uploading the files, selecting the output file and converting the file online directly.

Convert.Files: MKV to MP4


Convertio is another free online MKV to MP4 converter. Not only local MKV file, it also lets you paste the URL only and get the MP4 conversion in output. Though it supports batch conversion, it requires you to sign up to convert more than 2 MKV files at the same time.

Convertio: MKV to MP4

Now, let’s check the differences among the three free online MKV to MP4 converters.

FeaturesFree Online Video ConverterConvert.FilesConvertio
Input formatsOver 30029Over 100
Output video formatsMP4, MOV, MKV, AVI, M4V, FLV, WMV, WEBM, VOB, MPG, 3GP, GIFAVI, 3GP, FLV, MPEG, VOB, WMV, MKV, ASF, M4V, F4V, 3G2, MP4, MOVMP4, AVI, WMV, MOV, MPEG, MPG, WebM, 3GP, FLV, TS, SWF, M4V, etc.
Output audio formatsMP3, AAC, AC3, WMA, WAV, AIFF, FLAC, MKA, M4A, M4B, M4RMP3, WAVMP3, WAV, M4A, WMA, AAC, FLAC, M4R, IMA, DTS, OGG, AIFF, PVF, WVE, AU CUDA, etc.
Converting speedFastMediumSlow
Convert URL
Batch conversion (Signup)
File size limitNoNoYes
Video settingsEncoder, frame rate, resolution, bitrate
Audio settingsEncoder, sample rate, channel, bitrate
Resolution adjustment

From the above table, you could easily find Free Online Video Converter is the best one with no limit for file size.

Convertio is the ideal one option when you want to convert URL MKV to MP4.

Part 3. How to convert MKV to MP4

In this part, we will take the easy MKV to MP4 converter, to show you how to convert MKV to MP4 online.

Step 1. Go to the page of Free Online Video Converter, Click “Add files to convert” button. Then you will need to download the launcher, and install it.

Step 2. In the popup, add the MKV file or files that you want to convert to MP4.

Step 3. Select “MP4” in output file, and click “Convert” to start to convert and download the MP4 files to your computer directly.

If you would like, just click the settings image next to the output file to adjust the video and audio codec, resolution, etc.

Convert MKV to MP4 Online

Part 4. FAQs About MKV to MP4 Converter Online

How do I open an MKV file?

Since MKV is not an industry-standard format, it is not widely adopted if you want to play MKV video, using VLC Player or a tool to convert it to other popular formats first and then watch it on other players.

Why is MKV not supported?

Specific codecs are required to play MKV files. However, some mainstream video players, such as Windows Media Player, do not have a special codec for MKV, so they cannot play it properly.

How to choose between MKV and MP4?

Each of these two formats has strengths; you can choose according to your needs. If you want to save a higher-quality video, choose MKV. If you want to save the video in a smaller size and distribute it easily on the internet, MP4 is a better choice.

What are the advantages of MKV?

MKV supports high-quality video and can hold numerous images, videos, subtitles, and audio in a single file. And it contains a wider range of video and audio codecs compared with other popular video formats.

How to Convert MKV to MP4 on Mac?

Since Apple doesn't support MKV format, you can't use iMovie to convert MKV to MP4. VLC Player will be your best choice. Or you can open Vidmore Free Online Video Converter directly on your Mac browser to help you convert.


This post mainly talks about the 3 free online MKV to MP4 converters, and make the simple introduction of MKV and MP4. Converting MKV to MP4 can be achieved by the 3 online video converters, and you find the best one solution according to your needs.

Convert video
Free Online Video Converter

The best online app to convert AVI to MP4 with high quality.

Try It Now


Vidmore Video Converter Icon

Try Vidmore Video Converter for Free

All-in-one toolkit for converting and editing video & audio files in Windows 11/10/8/7, Mac OS X 10.12 and higher

Free Download Free Download

based on 176 user reviews

Close Pop