What is an SRT file? How to open, create and edit one

If you have ever downloaded subtitles for a film, you have almost certainly ended up with a file ending in .srt. It is the most common subtitle format in the world, supported by virtually every media player on every device. But what actually is an SRT file, what is inside it, and how do you open, edit or play one? This guide answers all of that in plain English. No prior knowledge needed.

What an SRT file is

An SRT file (short for SubRip Subtitle) is a plain-text file that holds the subtitles for a video. It contains the lines of dialogue and the exact times each line should appear and disappear. The name comes from SubRip, a program that originally extracted (“ripped”) subtitles from DVDs.

The crucial word is plain text. An SRT file contains no video, no audio and no images, just text and timestamps. That is why it is tiny (a full-length film’s subtitles are often under 100 KB) and why it works almost everywhere. There is nothing complicated to decode. It sits next to your video file and your player combines the two on the fly.

What is inside an SRT file

Open an SRT file in any text editor and you will see a simple, repeating pattern. Each subtitle, called a cue, is made of four parts.

1
00:00:04,000 --> 00:00:06,500
It's a beautiful day
in the neighbourhood.

2
00:00:07,000 --> 00:00:09,200
Won't you be my neighbour?

Reading one cue from top to bottom, you find

1. a sequence number, with cues numbered 1, 2, 3 and so on, in order;
2. a timing line, which gives the start time, then -->, then the end time, with each timestamp written as hours:minutes:seconds,milliseconds. Note the comma before the milliseconds. That comma is a defining feature of SRT;
3. the text, one or more lines of dialogue to show on screen during that time window;
4. a blank line separating this cue from the next.

That really is the entire format. An SRT file is just this block repeated for every line in the video. It also supports a few basic HTML-style tags such as <i> for italics and <b> for bold, which most players honour, but it has no concept of fonts, colour, exact position or karaoke timing. For those you need a richer format like ASS, covered in the guide on subtitle formats explained.

How to open an SRT file

Because it is plain text, you can open an SRT file two different ways depending on what you want to do.

To read or edit the text

Open it in any text editor.

• Windows. Notepad works (right-click the file, then Open with → Notepad). Notepad++ is a better free option.
• macOS. TextEdit, or a code editor like VS Code.
• Anywhere. Any plain-text editor will do. Avoid full word processors like Microsoft Word, which can add invisible formatting that breaks the file.

To watch it with a video

You do not “open” an SRT file to watch it. You load it alongside the video in a media player. The easiest method works in almost every player. Put the .srt file in the same folder as the video and give it the same name, so Movie.mp4 pairs with Movie.srt. Most players (VLC, MPC-HC, Plex, Jellyfin, the Windows Movies & TV app) then load the subtitles automatically when you play the video. You can also drag a .srt file straight into a playing VLC window to add it on the spot.

How to create or edit an SRT file

Since it is just text, you can make an SRT file by hand. Open a new file in a text editor, type cues in the pattern shown above, and save it with a .srt extension and UTF-8 encoding (more on that below). To edit existing subtitles, perhaps fixing a typo or removing a line, open the file, change the text, and save. There are only a few rules to respect.

• Keep the numbering, the timing line and the blank-line separator intact.
• Keep the timestamp format exact. 00:00:04,000 has two digits for hours, minutes and seconds, a comma, then three digits of milliseconds.
• The end time of a cue must be after its start time.

If you would rather not touch the timing by hand, that is exactly what subtitle tools are for. See the common problems below.

Common SRT problems (and how to fix them)

Three issues account for almost every “broken” SRT file, and none of them mean the file is beyond saving.

The subtitles are out of sync

The text is right but appears too early or too late. If the gap is constant the whole way through, you simply need to shift the subtitle timing by a few seconds. If the subtitles start in sync but drift further off as the film plays, that is a frame-rate mismatch, fixed with the frame-rate converter. The guide on why subtitles go out of sync explains how to tell the two apart.

The accented characters are garbled

If you see café instead of café, or boxes and question marks where letters should be, the file was saved in the wrong character encoding. Re-decoding it to UTF-8 with the encoding repair tool restores the correct characters. To prevent it, always save SRT files as UTF-8.

A player won’t accept the SRT at all

Some web and HTML5 players only read WebVTT, not SRT. In that case, convert the SRT to VTT and it will load. The reverse is true for some TVs that only want SRT.

SRT versus other subtitle formats

SRT is the universal default, the one to reach for whenever you want maximum compatibility. Its close cousin WebVTT (.vtt) is what browsers and HTML5 video require. It is almost identical, but with a period instead of a comma in the timestamps and a WEBVTT header. ASS/SSA (.ass) is the heavyweight, carrying fonts, colours, positioning and karaoke for anime and stylised captions. You can move between all three losslessly for the timing and text. Only styling that a simpler format cannot represent gets dropped. There is a full comparison in subtitle formats explained.

The short version

An SRT file is the simplest, most widely supported way to store subtitles. It is plain text, a numbered list of cues, each with a start time, an end time and a line or two of dialogue. You can open it in any text editor to read or edit it, and play it by dropping it next to your video with a matching name. When one misbehaves, it is almost always a sync issue or an encoding issue, both quick to fix, rather than anything wrong with the format itself. Understand those few ideas and the humble .srt file stops being mysterious for good.