SRT vs VTT: which subtitle format do you need?

SRT and VTT are the two subtitle formats you meet most often. Both are plain text files with a start time, an end time and the words to show. The differences are small, but they decide whether your subtitles appear at all.

SRT in one minute

SRT comes from SubRip, an old program for ripping subtitles from DVDs. Each subtitle — each cue — has a number, a time range and one or more lines of text, separated from the next cue by an empty line:

1
00:00:01,000 --> 00:00:03,500
Good morning, let's begin.

2
00:00:04,000 --> 00:00:06,200
First, the migration status.

Note the comma before the milliseconds. SRT has no official specification, which is why different programs accept slightly different variants, and it has no standard way to position text on screen.

WebVTT in one minute

WebVTT (Web Video Text Tracks) is a W3C specification made for video on the web. A VTT file must start with the word WEBVTT, uses a dot before the milliseconds, and the hours may be left out:

WEBVTT

00:01.000 --> 00:03.500
Good morning, let's begin.

00:04.000 --> 00:06.200 line:0
First, the migration status.

Cue numbers are optional. After the time range a cue can carry settings such as line, position or align, which place the text on screen — in the example above, line:0 moves it to the top.

Which one to use

• A video on your own website: VTT. The HTML <track> element, which browsers use to show subtitles over a video, takes WebVTT files.
• YouTube: either. YouTube accepts both; its help pages say that for SRT only basic files are supported, without styling, while for VTT positioning is supported and styling is limited to bold, italic and underline.
• Video editors, media players and TVs: SRT is the safe choice — it is the format they accept most widely. Check your program's documentation when in doubt.

If you are not sure, keep both: most subtitle tools, SonaFact included, export SRT and VTT from the same transcript.

Converting without losing timing

Converting between the two is mostly mechanical: the comma becomes a dot or the other way round, the WEBVTT header is added or removed, cue numbers are added for SRT. What can be lost is what SRT cannot express — positioning settings and VTT-specific tags such as voice labels are dropped when you go from VTT to SRT.

You can do it in the browser, without uploading the file, with our free SRT ↔ VTT converter. If the subtitles are out of sync with the video, the time shift tool moves every cue by the same amount.

One more check: readability

Whichever format you choose, subtitles only help if people can read them in time. Common subtitling guidelines keep lines to about 42 characters, use at most two lines per cue and keep the reading speed around 17 characters per second. The readability checker lists every cue that breaks one of these limits.

Try it on your own recording

The free plan gives you 3 transcripts a day, up to 30 minutes each, without a card — enough to judge the transcript, the speakers and the editor yourself.