How to Convert WebM to MP4 [Step-by-Step Guide]

Introduction

WebM and MP4 are two widely used video formats, but they serve very different purposes. While WebM is optimized for web playback, MP4 offers near-universal compatibility across operating systems, mobile devices, TVs, and editing software. As a result, converting WebM to MP4 is often necessary for smooth playback, easier sharing, or professional editing.
In this guide, you'll learn multiple ways to convert WebM to MP4, including the powerful FFmpeg command-line tool, user-friendly applications like HandBrake, VLC Media Player, and online converters. And if you want the simplest and most stable solution with high-quality results, UniFab Video Converter provides a fast, modern alternative designed for both beginners and advanced users.

What is FFmpeg?

FFmpeg is a free, open-source software project that enables conversion, editing, and processing of video, audio, and other multimedia files. Known for its versatility, FFmpeg supports a wide range of formats, making it a popular choice for file conversions like converting WebM to MP4.

WebM vs. MP4: What's the Difference?

Understanding the differences between WebM and MP4 can clarify why you might want to convert from one to the other.

• WebM: A format primarily designed for web streaming, WebM is optimized for online video playback and supports VP8/VP9 codecs. However, it has limited compatibility outside web browsers and select media players.
• MP4: MP4 is a widely supported format compatible with nearly all devices and platforms, including smartphones, consoles, and streaming services. It typically uses H.264 or HEVC for video compression, delivering high-quality output suitable for both online and offline use.

Why Convert WebM to MP4?

✅ Greater Device Compatibility – MP4 files work on almost any device, while WebM has limited support, especially on Apple devices.

✅ Improved Offline Accessibility – MP4 is better for offline viewing and sharing, making it more versatile across platforms.

✅ Better Quality and Codec Support – MP4 supports high-quality encoding with widely used codecs like H.264 and H.265, ensuring better playback and compression efficiency.

✅ Broader Software Compatibility – MP4 files are supported by most video editing software, whereas WebM may require additional codecs or conversions.

How to Convert WebM to MP4 Using FFmpeg

Follow these steps to convert WebM to MP4 with FFmpeg:

1. Install FFmpeg: Ensure FFmpeg is installed on your system. If FFmpeg isn't already installed, download it from the official FFmprg website. Installation instructions:

• macOS: brew install ffmpeg

• Ubuntu/Debian: sudo apt update && sudo apt install ffmpeg

• Windows: Download from the official FFmpeg website or use Chocolatey:choco install ffmpeg

2. Open Command Prompt/Terminal: Navigate to the directory containing your WebM file using the command line.

3. Basic Conversion Command: The simplest command to convert a WebM file to MP4 is: ffmpeg -i input.webm output.mp4. Replace input.webm with the actual name of your WebM file and output.mp4 with your desired output filename.

4. Specifying Codecs for Compatibility: For broader compatibility, particularly with older devices or software, it is recommended to explicitly set the video and audio codecs to H.264 (libx264) and AAC, respectively:  ffmpeg -i input.webm -c:v libx264 -c:a aac output.mp4

5. Adjusting Quality and Bitrate (Optional): You can fine-tune the output quality and file size by adjusting parameters like bitrate and preset:

• Video Bitrate: -b:v 1000k (sets video bitrate to 1000 kbps)

• Audio Bitrate: -b:a 128k (sets audio bitrate to 128 kbps)

• Preset: -preset medium (trades encoding speed for file size/quality; options include ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow)

• CRF (Constant Rate Factor): -crf 22 (for H.264, a lower CRF value means higher quality but larger file size; 22 is a common balance)

6. Add Audio Codec (If Needed): For greater compatibility, specify the audio codec:ffmpeg -i input.webm -c:v libx264 -c:a aac output.mp4. This ensures MP4 uses H.264 for video and AAC for audio, widely supported across devices.

7. Execute the Command: Press Enter to run the command and initiate the conversion. The time taken will depend on the file size, your system's performance, and the chosen settings.

How to Convert WebM to MP4 on Mac Using HandBrake

HandBrake is a free, open-source video transcoder that works perfectly on macOS. It supports WebM, MP4, MKV, and many other formats. If you prefer a graphical interface instead of command-line tools like FFmpeg, HandBrake offers an easy and reliable way to convert WebM files to MP4 on your Mac.
Follow the detailed steps below:

1. Download and Install HandBrake: Visit the official HandBrake website and download the macOS version. After downloading, open the .dmg file and drag HandBrake to your Applications folder. Launch the app.

2. Import Your WebM File: You can load your WebM file in two ways:

• Drag and drop the WebM file directly into the HandBrake window
• Or click "Open Source" and select your WebM file from Finder

Once loaded, HandBrake will scan the file and display its basic information, including resolution, framerate, and duration.

3. Select MP4 as the Output Format: In the Summary tab, go to the Format dropdown list and choose MP4. This ensures broad compatibility with macOS, iOS, Windows, smart TVs, streaming platforms, and most editing software.

4. Choose a Preset for Optimal Quality: HandBrake provides a range of presets tailored for different use cases:

• Fast 1080p30 – Best balance of speed and quality
• HQ 1080p30 Surround – Higher quality, slower encoding
• Fast 720p30 – Good for smaller file sizes
• Production Standard – For editing workflows
• Custom Profiles – Match settings to your source video

Select a preset based on your desired quality and performance. For most users, Fast 1080p30 is ideal.

5. Choose the Output Location and File Name: Click Browse next to the "Save As" field and choose where you want the converted MP4 file to be saved. Assign a clear file name and confirm the destination folder.
6. Start the Conversion: Once the settings look correct, click the Start Encode button at the top toolbar. HandBrake will begin converting your WebM file to MP4.
7. Locate Your Converted MP4: After the encoding process completes, HandBrake will notify you. Go to the output folder you selected earlier to find the newly created MP4 file.

How to Convert WebM to MP4 Using VLC Media Player

VLC Media Player is a free, open-source multimedia application available for Windows, macOS, and Linux. It not only plays WebM files but also converts them into widely compatible formats like MP4. If you prefer a simple graphical interface instead of command-line tools, VLC offers a straightforward and reliable conversion workflow.

Follow the detailed instructions below to convert WebM to MP4 using VLC.

1. Open VLC Media Player: Launch VLC on your computer and go to the Media menu at the top-left corner.

2. Choose the Convert/Save Option: From the dropdown list, click Convert/Save to open the file selection window.

3. Add Your WebM File: Click the + Add button, browse your computer, and select the WebM file you want to convert.

4. Proceed to Conversion Settings: Once your file is added, click the Convert/Save button at the bottom of the window.

5. Select an MP4 Output Profile: In the Profile menu, choose an MP4-compatible profile such as Video – H.264 + MP3 (MP4). This ensures your output file is widely supported across most devices.

6. Choose Output Location and File Name: Click Browse to select where you want to save the converted file and assign a new file name ending with .mp4.

7. Start the Conversion: Click Start, and VLC will begin converting your WebM file into MP4. The progress bar at the bottom will indicate when the conversion is complete.

How to Convert WebM to MP4 Online

If you prefer not to install software like FFmpeg or VLC, an online converter offers the quickest way to convert a WebM file to MP4. These tools run directly in your browser and require no technical setup.

Here's a step-by-step guide on how to convert WebM to MP4 online:

1. Visit an Online Converter: Go to a trusted online conversion website such as Ezgif, VEED, or CloudConvert. These platforms provide a simple interface and support most WebM files.

2. Upload Your WebM File: Drag and drop your WebM file into the upload area, or click the Upload button to select the file from your computer. Most sites support files up to several hundred megabytes, depending on your internet speed.

3. Select MP4 as the Output Format: Choose MP4 from the available output format options. The tool will typically default to MP4 since it’s one of the most commonly requested export types.

4. Start the Conversion: Click Convert or Convert to MP4 to begin processing your file. Online converters automatically handle codec selection—no complex settings required.

5. Download Your MP4 File: Once the conversion finishes, click the Download button to save the MP4 file to your computer or mobile device.

The Simplest Way: Convert WebM to MP4 Using UniFab

UniFab Video Converter provides a simple and intuitive way to convert WebM to MP4 without dealing with command-line tools like FFmpeg or complex software interfaces such as VLC or HandBrake. Meanwhile, UniFab is faster, more stable, and delivers higher-quality results compared to online tools. With its GPU-accelerated engine and broad format support, UniFab is ideal for users who want a fast, high-quality conversion workflow on Windows or macOS.

Key Features

• Supports 1000+ Video Formats: Ensures compatibility with all devices, including mobile and portable options.
• Resize Without Quality Loss: Adjusts video size for platform requirements while maintaining high quality.
• Lossless Compression: Retains high-quality video and audio (TrueHD, DTS-HD, DTS X) for smooth sharing.
• Built-in Editor: Trim, rotate, crop, adjust aspect ratio, apply effects, add watermark, subtitles, audio, and speed adjustments.
• Advanced Settings: Customize resolution, codec, frame rate, bitrate, channels, and more.

Effortlessly Convert WebM to MP4 With UniFab

Conclusion

Converting WebM to MP4 can be done in many ways, depending on your workflow and comfort level. FFmpeg offers unmatched flexibility for power users, while HandBrake and VLC provide accessible desktop options. Online converters are convenient for small, quick tasks but may struggle with larger files or unstable uploads.
For the most streamlined experience, UniFab Video Converter stands out by combining speed, stability, and high-quality results without the limitations of browser-based tools. Whether you need advanced customization or a simple one-click workflow, you’ll find the right method in this guide to convert your WebM files to MP4 efficiently and reliably.

FAQs about WebM to MP4

Is WebM or MP4 Better Quality?

The quality of WebM and MP4 depends on the codec and bitrate. MP4 (H.264/H.265) generally offers excellent quality with efficient compression and wide compatibility. WebM (VP8/VP9) might provide slightly better quality at lower bitrates but isn't as universally supported. In most cases, the quality difference is minimal unless working with very high or low bitrates.

How Do I Change a WebM File to MP4?

To change a WebM file to MP4, you can use UniFab Video Converter, which offers a simple and user-friendly solution. With just a few clicks, you can easily convert your WebM files to MP4 format, ensuring high-quality output. UniFab supports various formats and provides customization options, making it an efficient tool for all your video conversion needs.

Is it safe to use FFmpeg?

FFmpeg is safe to use. It's a trusted open-source command-line tool designed for converting and processing video, audio, and other compressed media formats without any hidden threats.

What are the limitations of FFmpeg?

Some limitations in FFmpeg arise from codec and container compatibility, which may restrict video frame size, frame rate, or bitrate. Always review the specifications of your chosen codec and container format to ensure they meet your needs.

Do I need a powerful computer for FFmpeg or UniFab? 

FFmpeg runs well on most computers, but performance and conversion speed can vary. For faster processing, UniFab leverages CPU and GPU acceleration on multi-core systems, enabling quicker results, especially on more advanced setups.

Can VLC Player convert WebM to MP4?

Yes, VLC Media Player can convert WebM to MP4. VLC includes a built-in file conversion feature that lets you change WebM into widely supported formats like MP4. Simply open VLC, go to Media > Convert/Save, add your WebM file, choose an MP4 profile (such as Video – H.264 + MP3 (MP4)), set your destination file, and click Start to begin the conversion.

Is converting WebM to MP4 free?

Yes, converting WebM to MP4 can be done for free. Tools like FFmpeg, HandBrake, and VLC are completely free, and many online converters also offer free WebM-to-MP4 conversion. Some paid software may provide faster processing or higher-quality outputs, but free options are fully capable for most users.