2026-09-28

SRT vs VTT: the difference between the two subtitle formats

SRT and VTT are both plain-text subtitle files. VTT adds a WEBVTT header, dot milliseconds, positioning and styling, and is what HTML5 players read.

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SRT and VTT are both plain-text subtitle files that pair each line of text with a start and an end time. SRT (SubRip) is the basic one: numbered blocks with a comma before the milliseconds. VTT (WebVTT) starts with a WEBVTT header, puts a dot before the milliseconds, and adds cue settings for position and optional CSS styling. It is the format the HTML <track> element reads.

So pick the format your destination asks for: VTT for a web player, either one for YouTube. The format rules below come from MDN's WebVTT format and <track> element pages and YouTube Help's supported subtitle files page, read on 2026-09-28.

What is the difference between SRT and VTT?

The SRT column follows the SubRip example and rules on YouTube's help page; the VTT column follows MDN.

From MDN WebVTT, MDN <track>, and YouTube Help, read 2026-09-28.
Part	SRT (.srt)	VTT (.vtt)
First line	The first block's number	`WEBVTT`, the only required part of the file
Cue numbers	Each block starts with a number	Optional identifiers; numbering them is common
Time format	`00:00:00,599 --> 00:00:04,160`	`mm:ss.ttt` or `hh:mm:ss.ttt`, joined by `-->`
Position	YouTube points to its advanced formats, not SRT, for positioning	Cue settings such as `line`, `position`, `size`, `align`
Styling	YouTube recognizes no style markup	`STYLE` blocks with the `::cue` pseudo-element
Encoding	Plain UTF-8 on YouTube	UTF-8; MIME type `text/vtt`
HTML5 `<track>`	Not the format MDN documents	The format `<track>` files use

What does an SRT file look like?

A number, a time line, the text, then a blank line before the next block. This follows the SubRip example on YouTube's help page:

1
00:00:00,599 --> 00:00:04,160
Three steps to a captioned video.

2
00:00:04,160 --> 00:00:06,770
First, write the script.

What does a VTT file look like?

The same two cues in WebVTT. MDN lists five cue settings (vertical, line, position, size, align); here line:-1 places the first cue at the bottom, since MDN counts negative line numbers from the bottom up:

WEBVTT

1
00:00:00.599 --> 00:00:04.160 line:-1
Three steps to a captioned video.

2
00:00:04.160 --> 00:00:06.770
First, write the script.

Which one should I use?

A website or web app: VTT. MDN says <track> files are formatted in WebVTT, with kind values such as subtitles and captions.
YouTube: either. Its help page lists SubRip (.srt) as a basic format, with only basic files supported and no style info recognized, and WebVTT (.vtt) as an advanced format in initial implementation: positioning is supported, and styling is limited to <b>, <i>, and <u>.
Another platform or player: use the format its own upload page names.

How do I convert SRT to VTT?

Add WEBVTT and a blank line at the top, and change the comma before the milliseconds to a dot in every time line. The SRT numbers can stay: in WebVTT they become cue identifiers, which MDN says do not have to be unique. Save the result as UTF-8 with a .vtt extension. Going from VTT to SRT, reverse it: remove the header, any STYLE, REGION, or NOTE blocks, and the cue settings, number every block, and change each dot before the milliseconds back to a comma. YouTube recognizes no style markup in SRT files, so styling does not carry over.

Do burned-in captions need an SRT or VTT file?

No. Burned-in captions are drawn into the picture, so there is no file to ship; Hard subtitles vs soft subtitles explains the trade-off. Sume's captions API burns captions but takes no SRT upload: send phrase-level cues with text, start, and end in seconds instead, as How to burn an SRT file into a video shows. It returns the captioned video, not a subtitle file. To write an .srt or .vtt from speech, see How to generate an SRT file from a video.