What quality should I expect from the SUB output?

Our converter preserves as much fidelity as MicroDVD Subtitle allows. Where WebVTT Subtitle carries information that MicroDVD Subtitle cannot represent, that information is mapped to the closest equivalent (for example, color spaces, codec parameters, or metadata fields). For most everyday uses the result is indistinguishable from the source.

Are my subtitle timings preserved exactly when converting VTT to SUB?

Yes. Start times, end times, and durations are copied with millisecond precision. If the source uses frame-based timing rather than millisecond timing, we use the file's declared frame rate to convert — verify the result against your video, especially for long files where small timing errors accumulate. Styling (colours, positioning) is preserved when both formats support it; MicroDVD Subtitle may strip styles that have no equivalent.

What file size should I expect for the SUB output?

The output size depends on the content and the compression characteristics of MicroDVD Subtitle. In most cases the SUB file will be in the same ballpark as your VTT input, with differences driven by how each format encodes data. There is no fixed ratio — the converter does not change quality settings unless you ask it to.

When should I convert VTT to SUB instead of staying with VTT?

Convert when the application, device, or workflow you are targeting prefers MicroDVD Subtitle over WebVTT Subtitle. If your current VTT file already opens and behaves correctly everywhere you need it to, there is no benefit to converting — keep the original. The most common reasons to switch are compatibility (a tool only accepts SUB), distribution (recipients expect SUB), or feature requirements specific to MicroDVD Subtitle.

What is the maximum VTT file size I can convert?

MegaConvert accepts VTT files up to 100 MB on the free service, which is enough for the vast majority of real-world WebVTT Subtitle files. If you have a larger file (typical for high-resolution video or uncompressed audio), please contact us — we can sometimes accommodate larger uploads for legitimate use cases.

Is my VTT file safe and private when I upload it?

Yes. Your VTT file is uploaded over HTTPS, processed in an isolated job environment, and deleted from our servers within one hour. We do not read, index, store, or share the contents of your file. No account is required, so the upload is not associated with a personal identity. See our privacy policy for the full details.

Convert VTT to SUB

Free online VTT to SUB converter. No signup required.

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Max file size: 100 MB

Why Convert VTT to SUB?

Understand when and why this conversion makes sense for your workflow.

Converting WebVTT Subtitle to MicroDVD Subtitle ensures your subtitle or caption file works correctly with your target video player, streaming platform, or editing tool. Subtitle formats differ in how they encode timing information, styling, positioning, and special characters. A subtitle file that displays perfectly in one player may fail entirely in another, making format conversion essential for any video production or distribution workflow.

WebVTT Subtitle has a known limitation: not as widely supported by desktop media players as SRT. In contrast, MicroDVD Subtitle offers a key advantage: frame-accurate timing that precisely matches video frame boundaries. While WebVTT Subtitle is commonly used for html5 web video subtitles and closed captions, MicroDVD Subtitle is better suited for legacy subtitle files for video content.

Convert your VTT subtitle file to SUB with MegaConvert and ensure your captions display correctly in every player and platform you target.

VTT vs SUB: Format Comparison

Side-by-side comparison of the source and target formats.

Property	VTT (Source)	SUB (Target)
Extension	.vtt	.sub
Full Name	WebVTT Subtitle	MicroDVD Subtitle
Compression	Varies	Varies
File Size	Medium	Varies
Best For	HTML5 web video subtitles and closed captions	Legacy subtitle files for video content
Browser Support	Wide	Varies

How to Convert VTT to SUB

Follow these simple steps to convert your file in seconds.

Upload your VTT subtitle file
Choose your .vtt subtitle file. UTF-8 encoded files are strongly preferred — Windows-1252 or other legacy encodings can corrupt non-Latin characters during conversion. The file picker accepts any size of subtitle file you are likely to encounter.
Click "Convert to SUB"
Press convert. Each subtitle cue is parsed from the WebVTT Subtitle source — start time, end time, text, and any styling — and re-emitted in MicroDVD Subtitle format. Timings are preserved with millisecond precision; styles are mapped to their closest MicroDVD Subtitle equivalent.
Wait for the conversion to complete
The conversion usually takes just a few seconds. The progress bar updates in real time while your WebVTT Subtitle file is processed and the new MicroDVD Subtitle file is generated.
Download your .sub file
When the conversion finishes, click the download link to save the new MicroDVD Subtitle file to your computer. The file is yours — no watermarks, no expiration on the file itself, and no MegaConvert account is required to download it.

Tips for Converting VTT to SUB

Practical advice to get the best results from this conversion.

Why this conversion is worth doing

WebVTT Subtitle has a known limitation: not as widely supported by desktop media players as SRT. MicroDVD Subtitle addresses this with a key advantage: frame-accurate timing that precisely matches video frame boundaries. Converting from VTT to SUB is most worthwhile when this specific trade-off matters for the way you intend to use the file.

Match the format to the actual workflow

WebVTT Subtitle is most commonly used for html5 web video subtitles and closed captions, while MicroDVD Subtitle is the standard for legacy subtitle files for video content. If your workflow is closer to the second pattern, converting makes sense. If you are still working in a context where VTT is the norm, converting may create unnecessary compatibility friction with collaborators or tools that expect the source format.

Watch for this limitation in the SUB output

MicroDVD Subtitle has its own limitation worth understanding before you commit: frame-based timing requires knowledge of video frame rate for correct display. After the conversion completes, open the SUB file and verify that this limitation does not affect your specific use case — for some workflows it is irrelevant; for others it can be a deal-breaker.

Match the subtitle format to your player or platform

Different players and platforms require specific subtitle formats. SRT is the most universally supported format for offline players. VTT (WebVTT) is the standard for HTML5 video on the web. ASS/SSA supports advanced styling but has limited player compatibility. Choose the format your target platform natively supports to avoid display issues.

Understanding VTT and SUB Formats

Learn about the source and target file formats to understand what happens during conversion.

Source Format

WebVTT Subtitle

text/vtt

WebVTT (Web Video Text Tracks) is the W3C standard subtitle and caption format designed for use with HTML5 video elements. It is based on SRT with additional features including CSS-based styling, cue positioning, vertical text support, and chapter markers. WebVTT is the only subtitle format natively supported by all modern web browsers for HTML5 video playback.

Advantages

W3C standard natively supported by all modern web browsers
Supports CSS styling, positioning, and vertical text
Includes metadata regions for accessible closed captioning

Limitations

Not as widely supported by desktop media players as SRT
Styling features are inconsistently implemented across browsers
More complex than SRT for simple subtitle use cases

Common Uses

HTML5 web video subtitles and closed captions
Streaming platform subtitle delivery (HLS and DASH)
Accessible web video captions meeting WCAG guidelines

Target Format

MicroDVD Subtitle

text/x-sub

SUB (MicroDVD Subtitle) is a frame-based subtitle format that uses frame numbers rather than timestamps for timing synchronization. Each line contains start and end frame numbers enclosed in curly braces followed by the subtitle text, with pipe characters separating multiple display lines. SUB requires knowing the video frame rate to correctly synchronize subtitle display timing.

Advantages

Frame-accurate timing that precisely matches video frame boundaries
Simple format that is easy to parse and generate programmatically
Supported by many popular media players including VLC

Limitations

Frame-based timing requires knowledge of video frame rate for correct display
Changing the video frame rate misaligns all subtitle timing
Less intuitive than timestamp-based formats for manual editing

Common Uses

Legacy subtitle files for video content
Frame-accurate subtitle synchronization for specific video encodes
Subtitle conversion source for timestamp-based format output

Frequently Asked Questions

Common questions about converting VTT to SUB.

Related Conversions

Explore other conversions related to VTT and SUB.

Other conversions from VTT

VTT to SRT VTT to ASS VTT to SSA VTT to JSON

Other conversions to SUB

SRT to SUB ASS to SUB SSA to SUB JSON to SUB

Convert VTT to SUB

Why Convert VTT to SUB?

VTT vs SUB: Format Comparison

How to Convert VTT to SUB

Upload your VTT subtitle file

Click "Convert to SUB"

Wait for the conversion to complete

Download your .sub file

Tips for Converting VTT to SUB

Why this conversion is worth doing

Match the format to the actual workflow

Watch for this limitation in the SUB output

Match the subtitle format to your player or platform

Understanding VTT and SUB Formats

WebVTT Subtitle

Advantages

Limitations

Common Uses

MicroDVD Subtitle

Advantages

Limitations

Common Uses

Frequently Asked Questions

What quality should I expect from the SUB output?

Are my subtitle timings preserved exactly when converting VTT to SUB?

What file size should I expect for the SUB output?

When should I convert VTT to SUB instead of staying with VTT?

What is the maximum VTT file size I can convert?

Is my VTT file safe and private when I upload it?

Related Conversions

Other conversions from VTT

Other conversions to SUB