What Is an SRT File? The Complete Guide to Subtitle Formats
Everything you need to know about SRT files: what they are, how they work, how to open and edit them, and how they compare to VTT, ASS, and other subtitle formats.
If you've ever downloaded a movie subtitle file, extracted captions from a video, or worked with any kind of closed captioning, you've almost certainly encountered SRT files. They're the most universally supported subtitle format in the world — and they're simpler than they look. This guide explains everything you need to know.
What does SRT stand for?
SRT stands for SubRip Subtitle. The name comes from SubRip, the software originally used to "rip" (extract) subtitles from DVDs in the early 2000s. The format it produced became an open standard and is now supported by virtually every video player, editing tool, and streaming platform in existence.
What does an SRT file look like?
An SRT file is a plain text file. You can open it in Notepad, TextEdit, or any text editor. Here's a typical example:
1
00:00:02,500 --> 00:00:05,000
Previously on Breaking Bad...
2
00:00:05,500 --> 00:00:09,000
We need to talk about your distribution.
3
00:00:10,200 --> 00:00:13,800
I'm not in the meth business.
I'm in the empire business.
Every subtitle cue has three parts:
- A cue number — sequential integers starting from 1
- A timestamp range — when the cue appears and disappears, in
HH:MM:SS,mmmformat - The subtitle text — one or more lines of dialogue
Cues are separated by a blank line.
How do SRT timestamps work?
The timestamp format is hours:minutes:seconds,milliseconds. The comma before the milliseconds is important — SRT uses a comma, while the related VTT format uses a period.
00:01:23,456 --> 00:01:26,789
This cue appears at 1 minute, 23 seconds and 456 milliseconds into the video, and disappears at 1 minute, 26 seconds and 789 milliseconds. The gap between the two timestamps is how long the subtitle is displayed on screen.
How to open an SRT file
Because SRT is plain text, you can open it with any of these:
- Notepad (Windows) — right-click the file → Open with → Notepad
- TextEdit (Mac) — works the same way
- VS Code or Sublime Text — better for larger files with syntax highlighting
- VLC Media Player — load the video, then drag the SRT file onto the player window to display it as subtitles
If Windows tries to open your SRT with a program that can't read it, right-click → Open with → Choose another app → Notepad.
How to edit an SRT file
Since it's plain text, you can edit any SRT file directly in a text editor — change dialogue, fix spelling, adjust timestamps manually. For common tasks, dedicated online tools are faster:
- Fix subtitle timing — use our Subtitle Time Shifter to shift all timestamps by a set amount
- Combine two subtitle files — use our Subtitle Merger
- Split a subtitle file at a specific point — use our Subtitle Splitter
- Fix overlapping cues — use our Subtitle Overlap Fixer
- Convert SRT to VTT — use our SRT to VTT Converter
All tools are free and run entirely in your browser.
SRT vs other subtitle formats
SRT vs VTT (WebVTT)
VTT is the web-native subtitle format used by HTML5 video players, YouTube, and Vimeo. The core structure is almost identical to SRT, with two main differences: VTT files start with a WEBVTT header line, and they use a period instead of a comma in timestamps.
Use SRT for desktop players and video editing. Use VTT for web video and streaming. Convert between them instantly with our VTT to SRT Converter or SRT to VTT Converter.
SRT vs ASS / SSA
ASS (Advanced SubStation Alpha) and SSA are subtitle formats that support rich styling — custom fonts, colours, positioning, karaoke effects. They're common in anime subtitles. SRT supports minimal styling only. If you need full typographic control, ASS is more capable; if you need broad compatibility, SRT wins.
SRT vs SBV
SBV is YouTube's native caption format. It's structurally very similar to SRT but uses a slightly different timestamp format. YouTube accepts SRT file uploads directly, which is usually the simplest approach.
SRT vs TTML / DFXP
TTML (Timed Text Markup Language) and DFXP are XML-based subtitle formats used in broadcast and streaming workflows. They're more complex than SRT but required by some platforms (Netflix uses a variant called IMSC). For most purposes, SRT is simpler and just as effective.
Does SRT support formatting?
SRT has limited, inconsistently supported formatting tags:
<b>bold</b>— bold text<i>italic</i>— italic text<u>underline</u>— underlined text<font color="#ffffff">text</font>— coloured text
Support varies by player. VLC and most smart TVs ignore font tags. If you need reliable styled text, VTT or ASS offer better formatting support.
What encoding should an SRT file use?
UTF-8 is the correct encoding for modern SRT files. It supports all languages and special characters. If your subtitles contain accented letters, Asian characters, Arabic, or any non-Latin script, UTF-8 is essential.
Older SRT files sometimes use Windows-1252 or other legacy encodings. If your subtitles show garbled characters (like é instead of é), the file is probably using the wrong encoding. Re-save it as UTF-8 in your text editor.
Common SRT file problems and how to fix them
Subtitles are out of sync. The most common issue. Use our Subtitle Time Shifter to shift all timestamps forward or backward until they align with the video.
Overlapping cues. Two cues cover the same time range, causing subtitles to stack or flicker. Use our Subtitle Overlap Fixer to detect and resolve overlaps automatically.
Cue numbers are out of order or duplicated. Some tools export malformed SRT files. The cue numbers need to be sequential from 1. You can renumber them by running the file through any of our tools, which always output clean, correctly numbered SRT.
Missing blank lines between cues. SRT requires a blank line between each cue. Without it, players may fail to parse the file. A good text editor with find-and-replace can fix this, or run the file through a validator.
FAQ
What program opens SRT files? Any text editor opens an SRT file for editing. For viewing subtitles with video, VLC is the most widely used free player and supports SRT natively.
Can I convert SRT to MP4? No — SRT is a subtitle file, not a video file. You can burn subtitles into an MP4 (called "hardsubbing") using ffmpeg or a video converter, but that's a different process from subtitle editing.
Are SRT files free to use? SRT is an open format with no licensing restrictions. The format is free for anyone to create, edit, or distribute.
Can SRT files contain multiple languages? No. A single SRT file contains one language track. For multilingual subtitles, you need separate SRT files for each language.
What's the maximum number of cues in an SRT file? There's no technical limit. Professional subtitle files for feature films might have 1,000 to 2,000 cues.
Why do my SRT subtitles look different in different players? Players render subtitles differently. Font size, position, colour, and outline are all controlled by the player, not the SRT file. To control appearance precisely, you'd need to use ASS format or burn the subtitles into the video.