SRT File - What Is It and How to Create One


What are SRT files?

Ever wondered how lines of dialogue make their way from basic words to the perfectly timed captions that appear on your screen?

Enter the SRT file, a SubRip subtitle file, which is essentially a simple text file that defines what and when captions appear on screen. SubRip is the software from which the file format takes its name and was developed in Europe.

These files work together with video, but contain only subtitle information. When an SRT file is loaded to a video platform that supports the format, the text will be displayed in the foreground of the video, according to the information contained in the file.

Although more sophisticated file formats exist, including ones where you can specify the style or positioning of captions, SRT files are the most widely used and supported of them all. The simplicity of the format becomes obvious from this little deconstruction of one caption block:

00:00:23,920 --> 00:00:28,560
That's the same weight
as around 450 adult elephants.

The first line, containing a single number (in this example 6), is the caption block number. These numbers give the order of the caption blocks, so the caption before this one would have number 5 as its block number, the following caption would have 7, and so on.

The next line down specifies the times at which the caption appears and disappears, known as timecodes. These timecodes correspond to the appropriate times in the video when the caption should be displayed.

Timecodes are given in the format hours : minutes : seconds , milliseconds. So, in this example, the caption would appear on screen 23 seconds and 920 milliseconds into the video, then disappear at 28 seconds and 560 milliseconds in.

Below the timecodes are the most important part of the block - the actual words of the caption. Each caption block tends to be one or two lines, with a 32-character limit on each line, arranged so they’re as readable as possible for the viewer. And - believe it or not - there’s a semi-science as to how this arrangement should be done!

Finally, the end of the caption is then denoted by an empty line which separates one block from the next.


Why use SRT files?

Ease of use

Since they’re so simple to create and update, SRT files are a hassle-free way to add captions to videos. Since they are just text files, they require no specialised software and can be edited in any basic text editor, such as Notepad or TextEdit. Additionally, since they’re such a widely used format, they’re compatible with virtually all platforms and players (such as Facebook, YouTube, Windows Media Player and many more).

Audience engagement

There is no denying that captions increase viewer engagement with video content:

  • 85% of all Facebook videos are watched without sound (Digiday)
  • Average shares on Facebook drop by around 15% when captions are removed
  • CTA (call to action) clicks fall by 26% when captions are removed
  • 10-second video views are 18% lower without captions

There is, quite literally, no good reason to not caption your video. You'll reach your viewers faster, keep them engaged for longer, provide access to deaf and hard of hearing audiences, and all this can be achieved through such a simple step.

Best of all, it works in any context. Captions help students retain content and take better notes, it improves literacy and reading skills and allows students to remain more engaged with the content.


Search Engine Optimisation, or SEO, refers to the process of increasing a website’s visibility and ranking in the online sphere. Captions are a simple way to reap SEO benefits when it comes to videos, since the automated bots that scan and index web pages do not readily process video data.

Adding a subtitle file to video content you upload to YouTube, for example, provides YouTube and other search engines with additional context and key words to help viewers find their way to your video.


How are SRT files created?

As mentioned, SRT files are simple enough that they can be produced in Notepad (if you’re using Windows) or TextEdit (if you’re using a Mac). To create your own SRT file for a video you’d like to subtitle, you’ll need to have the content of your captions and the relevant timecodes at hand.

In our text editor, we’ll start off with building our very first caption block, numbered 1. Keeping in mind the timecode format (hours : minutes : seconds , milliseconds) and remembering to separate timecodes with an arrow, we can make a block:

To build our second block, we need to remember to add an empty line between our blocks. Otherwise, we can build it in a similar way to the first block:

We can continue this process with sequentially numbered blocks until all the captions are complete.

Once we’re ready to save the completed SRT file, we can do so via the File -> Save menu, remembering to save as type *.srt:

If you’re on a Mac, this will look a little bit different. You’ll need to uncheck the ‘Hide extension’ and ‘If no extension is provided’ checkboxes:



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