SRT to VTT Converter — Required For HTML5 Video Captions

Introduction

SRT (SubRip) is one of the most common subtitle formats — plain, simple, and produced by most video editors, transcription tools, and captioning services by default. WebVTT (.vtt) is a related but separate format built specifically for the web: it's the format the HTML5 <track> element requires for adding captions or subtitles to a video on a webpage. If you have SRT captions — from a recorded lesson, an exported transcript, or a video editor — and you're publishing that video with native captions on your own site rather than through a platform that handles this for you, you need VTT specifically. SRT isn't accepted there.

What Actually Changes in the Conversion

Two things, and nothing more:

• A WEBVTT header line is added at the top of the file. Every valid WebVTT file has to start with this; SRT has no equivalent, so it's added fresh.
• Timestamps switch from a comma to a period before the milliseconds. SRT writes a timestamp like 00:00:20,000; WebVTT requires 00:00:20.000. That's the only formatting difference between the two formats' timecodes, and this tool converts every timestamp in the file accordingly. A line reading 00:00:20,000 --> 00:00:24,500 in your SRT file comes back as 00:00:20.000 --> 00:00:24.500, with the header added above it.

Your actual subtitle text, and the timing of when each line appears and disappears, is preserved exactly. Because SRT doesn't have any of WebVTT's extra features — things like on-screen positioning or styling cues, or a way to label who's speaking — there's nothing SRT-specific to lose in this direction. Converting SRT to VTT is a clean, complete translation, not a best-effort approximation.

Using the Converted File

A .vtt file on its own doesn't do anything until it's referenced from a video. The standard way to attach it is the HTML5 <track> element inside a <video> tag, with three attributes doing the real work:

• kind="captions" tells the browser what the track is for.
• src="lesson.vtt" points at the converted file.
• srclang="en" and label="English" identify the language, useful if you add more than one track later.

Once a track is referenced this way, the browser handles showing and hiding captions and lets viewers turn them on or off — nothing else has to be built for that to work.

What to Know Before You Convert

• Accepts .srt files up to 10 MB each. The file also has to genuinely be SRT-formatted — a validity check looks for real SubRip-style numbered timecodes, not just a .srt extension.
• Several files convert independently. Upload more than one and each becomes its own separate .vtt file; "Download all" bundles the finished files into a single ZIP, not one combined file.
• An empty or corrupted file is rejected with an error rather than silently producing a broken or blank result.

When This Is the Right Tool

• Publishing a recorded lesson with native captions. If you're embedding a self-hosted video with an HTML5 <track> element for captions — on a class website, a school-hosted page, or anywhere you control the video player — and your captions came out as SRT, this is the conversion you need before they'll work.
• Preparing captions from a tool that only exports SRT. Many transcription and captioning tools default to SRT output even when the destination expects WebVTT.
• Making video content usable for students who rely on captions — whether for accessibility, a noisy environment, or following along in a second language — on a page where you control how the video is embedded rather than relying on a platform's built-in captioning.

If your captions are already in WebVTT and you need the reverse, use Vtt To Srt instead.

Example

A teacher records a lecture and runs it through a transcription tool, which returns an SRT file with accurate timestamps. They want to embed the recording directly on their class webpage with captions built in, using a simple HTML5 video player rather than uploading to an external platform. The video element's caption track needs WebVTT, so they convert the SRT file here first, then reference the resulting .vtt file as the track source.

FAQs

What's the actual difference between SRT and VTT?

For a simple caption file like this tool produces, two things: WebVTT requires a WEBVTT header line, and its timestamps use a period before the milliseconds instead of SRT's comma. WebVTT can also carry extra features SRT doesn't have, like positioning and speaker labels, but converting from SRT has none of those to add since SRT never had them to begin with.

Why do I need VTT instead of SRT?

If you're adding captions to a video using the HTML5 <track> element — the standard way to attach captions to a self-hosted <video> — the format has to be WebVTT. SRT isn't accepted there, even though it's supported almost everywhere else.

Will my captions still be timed correctly?

Yes. Only the timestamp formatting and the header line change; the actual timing and text of every caption are preserved exactly.

What's the file size limit?

10 MB per file. A file must also genuinely be SRT-formatted to pass validation.

Is my subtitle file kept afterward?

No. Files are processed only to complete the conversion and are automatically deleted within 2 hours — see the Privacy Policy for details.

What if I need to go the other way, from VTT to SRT?

Use Vtt To Srt. That direction can lose WebVTT-specific styling and positioning information, since SRT has no equivalent for it — see that tool's page for details.