Subtitles6 min read

What is an SRT file

What's inside a .srt, why it's still the default subtitle format after thirty years, and the four mistakes that stop one from loading.

An .srt file is a text file. You can open it in Notepad, read it with your own eyes and edit it like any other. There's no video inside, no audio, no images: just sentences with the time they appear and the time they go away.

It was born inside a nineties program — SubRip, hence the name — built to rip the burned-in subtitles off a DVD. The program is long gone and the format stayed, because it turned out to be simple enough that everything could read it.

What's inside

One block per subtitle, all of them the same shape:

1
00:00:04,120 --> 00:00:06,480
Let's go over where we are
before we get into detail.

2
00:00:06,600 --> 00:00:09,000
The number that surprised me most
was the second-week drop-off.

Four things, in this order:

  1. A sequence number, starting at 1. None skipped.
  2. The timings, as hours:minutes:seconds,milliseconds. The --> arrow separates them.
  3. The text, on one or two lines.
  4. A blank line that closes the block. Without it, the player doesn't know where it ends.

That comma in front of the milliseconds is the format's signature, and it's also what separates it from a VTT file, which uses a dot.

What an SRT cannot do

Nothing else. And that is exactly why it's still here thirty years later.

No colours, no fonts, no on-screen position, no alignment, no backgrounds. It can't say "put this one at the top right because there's a caption at the bottom". It doesn't know who's speaking, beyond whatever you type into the text yourself. No metadata, no chapters, no multiple languages in one file.

An anime .ass does the first three; a WebVTT does nearly all of them. And still, when someone asks you for "the subtitles", they mean an SRT.

The four things that stop one from loading

An SRT that doesn't work almost always fails the same way. In order of frequency:

The encoding. If the file is saved as ANSI or Latin-1 and has accented characters, you get mojibake or nothing at all. Always save as UTF-8. If you open it in Notepad and see "reunión" instead of "reunión", this is it.

The byte-order mark. Three invisible bytes at the start of the file that some Windows editors add. Most players tolerate them; some swallow the first subtitle, and a few reject the whole file without telling you why.

Backwards or overlapping timings. A subtitle that ends before it starts, or that starts before the previous one has finished. One player ignores it; another skips from there to the end.

Broken numbering. Missing numbers, repeated ones, or a file starting at 0. Some programs — video editors especially — stop reading at the first gap.

All four are writing problems, not content problems: the text is fine and what's wrong is how it was saved. That's why a file that plays perfectly in VLC can be rejected by a platform's subtitle upload box.

Opening and editing one

Any plain-text editor: Notepad, TextEdit in plain mode, VS Code. Not Word: it will save it as .docx or slip smart quotes in where they don't belong.

If what you want is to shift timings, a text editor won't cut it and you want Subtitle Edit or Aegisub. But for fixing a typo or a misspelled name, Notepad is the right tool.

When what you want is the text, not the subtitles

An SRT is text chopped up to fit under a video: the sentence breaks every couple of seconds, and a paragraph ends up spread across five numbered blocks. Copy-pasting it into a document gives you something unreadable.

That's what our SRT to text converter is for: it joins sentences where the subtitle cut them, drops the numbering and leaves you real paragraphs. You can keep the timestamps if you'll use them to jump back to a moment in the recording.

And if you need the file in the other format, the SRT to VTT converter does the full conversion — header, escaping and milliseconds — without uploading anything anywhere.

And if you have no subtitles, only the video?

Then what you need isn't a converter but a transcript. Upload the recording and you'll get the text with timestamps, who speaks when, and a summary with the key points; the SRT falls out of that. First 45 seconds, no account and no card.

The tool for this

SRT to text converter

SRT to text converter

Turn any recording into text

Transcription with timestamps, speakers separated by name and a summary with the key points. The first 45 seconds are free and don't need an account.