How it Works

This tool supports conversion between four mainstream subtitle formats, covering most use cases.

SRT Format: The classic subtitle format with index, timestamp, text, and blank lines. Uses commas for milliseconds (e.g., 00:00:01,500). Has excellent compatibility—supported by nearly all players.
VTT Format: The HTML5 video standard format supporting advanced styling (alignment, positioning). Uses periods for milliseconds (e.g., 00:00:01.500) and requires a WEBVTT header.
ASS Format: Advanced SubStation Alpha, a professional subtitle format. Supports rich styling (fonts, colors, effects). Commonly used for anime and professional video production.
SUB Format (MicroDVD): Frame-based subtitle format using {startFrame}{endFrame}text structure. Requires specifying the video's FPS (frame rate) for accurate time conversion.

The converter uses an Intermediate Representation (IR) architecture—first parsing the source format into a unified time-text structure, then generating the target format to ensure conversion accuracy and format compatibility.

Common Usage Scenarios

🌐 Web Development

HTML5 <video> tags only natively support VTT files. Convert your SRT files to VTT for browser compatibility.

🎬 Video Editing

Professional editors like Final Cut Pro often require specific formats. Quick conversion saves time in high-pressure workflows.

📚 ELearning

Fix incompatible lecture subtitles for your local media player without downloading extra apps.

🔒 Privacy First

Subtitles can contain sensitive info. Local processing means your data never reaches a 3rd party server.

Frequently Asked Questions

Is my data safe during conversion?

Yes. The conversion happens entirely in your browser. Files are never uploaded to any server.

Does it support batch conversion?

Currently, we support converting one file at a time through paste or drag-and-drop.

Why does the VTT result not play?

Ensure the source SRT is correctly formatted. If the original has corrupted timestamps, the VTT will also fail validation.

Does it support non-English characters?

Yes, as long as the file is encoded in UTF-8. Other encodings (like GBK) might show garbled text.

Will I lose subtitle styling?

Basic text is preserved. Complex SRT styling tags may not translate 1:1 to VTT CSS styling.

Why are there periods in VTT timestamps?

That is part of the WebVTT standard specification. Periods are used instead of SRT's commas for milliseconds.

What is the WEBVTT header?

Every VTT file must start with this keyword to be identified correctly by browser engines.

Is this tool free to use?

Absolutely. It's free and always will be for our community of creators.

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Multi-Format Subtitle Converter - SRT/VTT/ASS/SUB