Top 8 AVI to MKV Converters: Convert AVI to MKV on Windows, Mac & Online (2026)

AVI vs MKV: Why Convert?

Before choosing a converter, it helps to understand what each format offers:

Common reasons to convert AVI to MKV: 

• Keep multiple audio languages in one file
• Embed subtitles without separate .srt files
• Reduce file size with modern codecs (H.265)
• Improve compatibility with modern players (Plex, Kodi, VLC)
• Preserve 4K or HDR content with proper container support

Quick Comparison: Top 3 AVI to MKV Converters

Best AVI to MKV Converters for Windows

1. UniFab Video Converter

Platform: Windows, Mac | Price: Free

Best for: Anyone who wants the best balance of speed, quality, and features in a free converter.

UniFab Video Converter is a free, full-featured video converter that handles AVI to MKV conversion with lossless quality and 50x GPU-accelerated speed. It supports batch conversion, custom codec settings, and built-in editing tools.

Key Features: 

• 1000+ formats support
• Lossless conversion preserving original audio and video quality
• 50x GPU acceleration (NVIDIA CUDA / AMD)
• TrueHD, DTS-HD, DTS-X audio codec support
• Customizable output settings (codec, resolution, frame rate, bitrate)
• Built-in editing: trimming, cropping, merging, flipping
• Batch conversion for multiple files 

How to Convert AVI to MKV with UniFab:

Step 1: Launch UniFab and select the Converter module. Drag and drop your AVI file or click Add to browse.

Step 2: Select MKV as the output format. Customize codec, resolution, and sample rate if needed. Click Start to begin conversion.

2. AVS Video Converter

Platform: Windows | Price: $49/year or $79 lifetime

Best for: Windows users who need broad format support with device-optimized presets.

AVS Video Converter supports 150+ formats with 4K Ultra HD quality and batch conversion capabilities. It includes ready-made templates for common output profiles.

Key Features: 

• 150+ format support including HD camera recordings
• 4K Ultra HD quality conversion
• Batch conversion with device-specific presets
• Audio and image extraction from video
• Subtitle conversion support
• Basic editing: splitting, cropping, merging

How to Convert AVI to MKV Using AVS Video Converter

Step 1: After opening this program on your Windows, head to the top to select the “To MKV” option > select “Browse” > add your preferred AVI video to the tool.

Step 2: Once you see the “Profile” drop-down menu, open it and select your appropriate preset. Then, select the “Convert Now” option to start the AVI to MKV conversion process.

Best AVI to MKV Converters for Mac

3. HandBrake

Platform: Windows, macOS, Linux | Price: Free (open source)

Best for: Mac, Linux, and Windows users who want a reliable, completely free converter.

HandBrake Video Converter is one of the most trusted free video converters available. Its open-source codebase, cross-platform support, and hardware-accelerated encoding make it a solid choice for AVI to MKV conversion on any operating system.

Key Features: 

• Supports nearly all common audio and video formats
• Built-in device presets (Apple, Android, PlayStation, Xbox)
• Hardware-accelerated encoding (Intel QSV, NVIDIA NVENC, AMD VCE)
• Batch conversion with chapter marker support
• Variable and constant frame rate support
• Subtitle passthrough and burn-in

How to Convert AVI to MKV Using HandBrake

Step 1: Once you open this free tool on your Mac, select the “Source” in the upper left side of the screen > Open File.

Step 2: Select your required AVI file for conversion > head to the “Destination” > select “Browse” to decide the location to save the converted MKV file.

Step 3: Next, select the “Start” option in the main window for completing the conversion process. 

4. VLC Media Player

Platform: Windows, macOS, Linux | Price: Free (open source)

Best for: Users who want a quick conversion without installing additional software.

VLC's built-in conversion feature can handle AVI to MKV conversion alongside its primary role as a media player. It is the most convenient option if you already have VLC installed.

Key Features: 

• 1000+ format support for playback and conversion
• No ads, tracking, or spyware
• Audio-video filters and subtitle synchronization
• Cross-platform and lightweight
• Completely free with no restrictions

How to Convert AVI to MKV Using VLC

Step 1: Open the VLC program on your Mac. Then, go to the “Media” menu at the upper left side of the program and select “Convert/ Save.”

Step 2: Go for the “Add” option in the menu > add your wanted AVI file for conversion.

Step 3: Under the “Output” section, select MKV > select “Convert” to start the AVI to MKV conversion process.

Best Free Online AVI to MKV Converters

5. CloudConvert

Best for: Users who need a reliable online converter with advanced customization options.

CloudConvert is a reliable online converter that supports 200+ formats with secure file handling. It offers advanced settings including codec selection, resolution adjustment, and subtitle options.

Key Features: 

• 200+ format support
• Custom codec, resolution, and quality settings
• API available for batch automation
• Secure: files deleted after conversion
• Free tier: 25 conversions per day

How to Convert AVI to MKV: Go to cloudconvert.com, select AVI to MKV, upload your file, adjust settings if needed, and click Convert.

6. VEED.io

Platform: Online | Price: Free (limited); Pro from $18/month

Best for: Users who want online conversion combined with basic editing features.

VEED.io is an online video editor with built-in format conversion. It supports Dropbox and YouTube imports and includes auto-subtitle generation.

Key Features: 

• No installation or account required for basic conversion
• Drag-and-drop upload
• Auto-subtitle generation
• Cloud import (Dropbox, YouTube)
• Built-in video editing tools

How to Convert AVI to MKV Using Veed.io

Step 1: You can open this program using any web browser. Upload your required AVI file to the tool using drag & drop option.

Step 2: Otherwise, on your device, select the Blue button to select the AVI file from the folder. You can also add the file from the Dropbox, YouTube URL, etc.

Step 3: Once you see the list of file types in the drop-down menu, select MKV as the output format. Then, select the “Convert File” option to begin the conversion process.

7. FreeConvert

Best for: Users who store files in cloud services and want seamless import.

FreeConvert supports cloud imports from Dropbox, Google Drive, and URLs, with 256-bit SSL encryption for secure file transfer. The free tier allows files up to 1GB.

Key Features: 

• Cloud integration (Dropbox, Google Drive, URL imports)
• 256-bit SSL encryption
• Customizable output settings
• Automatic file deletion after conversion
• 1GB max file size on free tier

How to Convert AVI to MKV: Go to freeconvert.com, select AVI to MKV, upload your file or import from cloud storage, adjust settings, and click Convert.

8. Converter App

Platform: Online | Price: Free

Best for: Users who need the simplest possible online conversion experience.

Converter App is a simple, no-frills online converter that processes files quickly without requiring account creation or software installation.

Key Features: 

• Device-independent conversion
• Supports audio, video, PDF, and image conversion
• No account or registration required
• Fast processing for small files

How to Convert AVI to MKV Using Converter App

Step 1: After opening this tool on your device using any browser, upload the AVI you want to convert to MKV format in the left-side upload box.

Step 2: The uploaded AVI file will be automatically converted to your selected MKV format within a few seconds.

Step 3: After finishing the auto-conversion, you will see a “Download” option, which you need to select for your desired results.

Full Comparison: All 8 AVI to MKV Converters

Tips for Best AVI to MKV Conversion Results

1. Choose the right codec — When converting, select H.265/HEVC for the best file size reduction while maintaining quality. H.264 is a safer choice for broader device compatibility.
2. Preserve audio tracks — If your AVI has multiple audio streams, ensure your converter supports passthrough to keep them in the MKV output.
3. Match resolution — Set the output resolution to match your source. Upscaling during conversion adds file size without improving quality.
4. Use GPU acceleration — If available (UniFab, HandBrake), enable GPU encoding to reduce conversion time significantly.
5. Check subtitle handling — If you have external .srt files, some converters can embed them into the MKV container during conversion.

FAQs about AVI to MKV

What is the best free AVI to MKV converter?

UniFab Video Converter is the best free AVI to MKV converter for desktop use. It offers lossless conversion, 50x GPU acceleration, batch processing, and built-in editing tools — all completely free. For a free online option, CloudConvert offers 25 free conversions per day with advanced settings, while HandBrake is the best free open-source alternative for Mac and Linux users.

How do I convert AVI to MKV without losing quality?

To convert AVI to MKV without quality loss, use a converter that supports "remuxing" or direct stream copy — this repackages the video and audio streams into the MKV container without re-encoding. HandBrake and UniFab both support this option. If you must re-encode (for codec change), use the highest bitrate settings available and match the source resolution and frame rate exactly.

Can I convert AVI to MKV online for free?

Yes, several online tools convert AVI to MKV for free. CloudConvert offers 25 free conversions per day with custom settings. FreeConvert handles files up to 1GB on the free tier. Converter App is completely free with no limits but offers basic functionality. Keep in mind that online converters require uploading your file to a server, which can be slow for large files and raises privacy concerns.

Is MKV better than AVI?

MKV is superior to AVI in most respects. MKV supports modern codecs (H.265, VP9, AV1) that offer better compression, multiple audio tracks and subtitle streams in a single file, chapter markers, 4K/HDR content, and smaller file sizes. AVI is a legacy format from 1992 that lacks these features. The only advantage of AVI is its universal compatibility with very old media players and devices.

How long does it take to convert AVI to MKV?

Conversion time depends on file size, codec settings, and your hardware. A simple remux (repackaging without re-encoding) takes seconds regardless of file size. Re-encoding with HandBrake takes roughly 2-5 minutes per GB on modern hardware. UniFab's 50x GPU acceleration can process a 30-minute AVI file in under 2 minutes when re-encoding. Online converters are slower because files must be uploaded and processed on remote servers.

Can I batch convert multiple AVI files to MKV?

Yes, UniFab, HandBrake, and AVS Video Converter all support batch conversion. Add all your AVI files to the conversion queue, set MKV as the output format, and start the process. HandBrake also supports encoding presets that apply the same settings to all files in the batch. Online converters typically do not support batch processing — you must convert one file at a time.

Will converting AVI to MKV reduce file size?

It depends on the conversion method. A simple remux (container change without re-encoding) produces virtually the same file size. Re-encoding with a modern codec like H.265/HEVC can reduce file size by 30-50% compared to the original AVI while maintaining similar visual quality. The trade-off is longer processing time and slightly increased computational requirements during encoding.

What is the difference between remuxing and re-encoding?

Remuxing copies the original audio and video streams directly into the new container format without any changes to the media data. It is instant, lossless, and produces the same quality. Re-encoding decodes the original streams and encodes them again with a new codec or settings. Re-encoding takes longer and can introduce minor quality loss, but it allows changing codecs, resolution, bitrate, and other parameters. For AVI to MKV, remux if you only want a container change; re-encode if you want to switch to a modern codec.

Can VLC convert AVI to MKV?

Yes, VLC Media Player includes a built-in conversion feature accessible through Media > Convert/Save. Add your AVI file, select MKV as the output profile, and start conversion. VLC's conversion feature is basic but functional for simple format changes. It does not offer batch processing through its GUI, and the conversion settings are more limited than dedicated converters like HandBrake or UniFab.

Are online AVI to MKV converters safe?

Reputable online converters like CloudConvert and FreeConvert use HTTPS encryption and auto-delete files after conversion. However, your video files are temporarily stored on their servers during processing. For sensitive or private content, use a desktop converter that processes files locally. Always check the converter's privacy policy and avoid unknown or suspicious conversion websites that may inject malware or ads into converted files.