What is an SRT file? SRT and VTT subtitles explained

SRT stands for SubRip Text, after SubRip, the program whose files made the format popular. They caught on because they're so simple: a text file you can open in any editor, with no styling and almost no rules. That's also why it was never formally standardized, and why WebVTT, the web's subtitle format, was built on it.

Each subtitle is a block of four parts: a number, the times it shows, one or more lines of text, and a blank line to end it.

1
00:00:01,000 --> 00:00:03,500
Nobody tells you this
when you start a channel.

2
00:00:03,600 --> 00:00:06,200
The first hundred videos
are practice.

• The number counts up from 1, in order.
• The times are hours, minutes, seconds and milliseconds, with a comma before the milliseconds, and --> between start and end.
• The text is a line or two. Some players read tags like <i> for italics; many, YouTube included, ignore them.

Any plain text editor opens one: Notepad on Windows, TextEdit on a Mac (in plain text mode), or a code editor. You can fix a word or a time by hand and save it. YouTube's own help suggests exactly that for fixing timings in a downloaded caption file.

Save it as UTF-8. SRT has no standard text encoding, and older files are often in Windows-1252, which turns accents and emoji into junk on other systems. YouTube only takes SRT files in plain UTF-8.

WebVTT (Web Video Text Tracks, .vtt) is the subtitle format browsers play. It looks almost the same as SRT, with a few changes:

WEBVTT

NOTE Made for the episode 12 clip

00:01.000 --> 00:03.500
Nobody tells you this
when you start a channel.

00:03.600 --> 00:06.200 line:80%
The first hundred videos
are practice.

Turning one into the other is mostly find and replace: add or remove the WEBVTT line, swap the commas and dots in the times, and add or drop the numbers. The free SRT to VTT converter does it both ways in your browser, and can shift every time at once.

When in doubt, keep an SRT: it's the one almost everything imports, and it converts to VTT in a second when something asks for that.

• From YouTube. If your video is on YouTube, it probably has automatic captions. In YouTube Studio, open Subtitles, pick the video and the language, fix the words in the editor (for automatic captions, Duplicate and edit first), then download the file from the Options menu.
• From a transcription tool. Most transcription apps and video editors export SRT. Check names, numbers and slang: that's where automatic transcripts slip.
• By hand. For a short clip, type it: play the video, note when each line starts and ends, and write the blocks as above. Keep each subtitle to a line or two that can be read in the time it's on screen.

A subtitle file sits beside the video, and the player draws it in its own style. Viewers can turn it off, and the video file has no words in it. Burned-in captions are drawn into the picture itself: they show everywhere the video goes, exactly as you designed them, and nobody can turn them off.

TikTok and Instagram can caption a video from its speech: TikTok lets you add auto captions when you edit a video and correct the text, and Instagram makes closed captions for reels with speech recognition. Viewers can turn both off, and they come in the app's plain style. The bold, word-by-word captions on clips that do well, a few words at a time with the word being said lit up, are burned in.

No SRT yet? The free auto caption generator makes one from a video's speech, on your device, and how to add subtitles to a video shows where to upload it on each app.

Already have an SRT? The free add captions to video tool burns it into a vertical video as word-by-word captions. Keep them clear of the apps' buttons with the safe zone checker, and see how to caption short videos for size, style and placement.

Every line early or late by the same amount? The file was timed for a version of the video with a different start, like one with an intro cut off. Shift every time by the difference: if the words come 2 seconds before they're said, add 2 seconds to all of them. The SRT to VTT converter shifts a whole file at once.

Fine at the start, further off as it goes? Then it was timed for a different cut or frame rate, and shifting won't fix it. Make the file again from the video you're actually using.

Only some lines off? Edit those times by hand, and keep each end time before the next line's start, or players show two subtitles at once.