SRT File Format (.srt)
An SRT file numbers each caption in order and gives it a start and end timecode measured in hours, minutes, seconds and milliseconds, with the line or lines of dialogue printed underneath and a blank line separating one caption from the next.
SRT at a glance#
| Full name | SubRip Subtitle |
|---|---|
| File extension | .srt |
| Category | Subtitles |
| Developer | Brain (SubRip) |
| First released | 2000 |
| MIME types | application/x-subrip |
| Compression | Uncompressed |
| FileFlip support | FileFlip reads and writes this format |
What a .srt file can hold#
These are the things a SRT file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Selectable text | Yes |
|---|---|
| Human readable | Yes |
Strengths and limitations of SRT#
What SRT does well
- Opens in every subtitle editor, video player and streaming platform in use today
- Plain text, so it can be read, edited or generated with nothing more than a text editor or a script
- Converts into almost any other subtitle format without loss, because it demands nothing back from the target
- Times captions by clock time, so it stays in sync regardless of the video's frame rate
Where SRT falls short
- Carries no styling, positioning or color, so every caption renders in the player's default look
- Has no official specification, only a widely copied convention, so edge cases vary by implementation
- The handful of HTML-style tags players do honor (bold, italic, color) are unofficial and inconsistently supported
- Cannot hold multiple subtitle tracks, chapter markers or metadata in a single file
Use SRT when the file needs to open in the widest possible range of players and sites and doesn't need positioning or styling.
Convert away from SRT when the destination needs something SRT cannot hold, such as WebVTT's on-screen cue positioning or ASS's karaoke timing and typesetting.
How to open a .srt file#
A .srt file opens in the programs below, grouped by the platform you are on. If you would rather not install anything, FileFlip converts SRT into a format your machine already opens, and it does it in the browser tab rather than on a server.
| Platform | Programs that open it |
|---|---|
| Windows | Subtitle Edit, VLC, Aegisub, Notepad |
| macOS | VLC, Aegisub, TextEdit, Subtitles |
| Linux | VLC, Aegisub, Gnome Subtitles, mpv |
| iOS | VLC, Infuse |
| Android | VLC, MX Player |
| Web | FileFlip |
SRT questions people ask#
What program opens an SRT file?
An SRT file opens in essentially any video player, including VLC, and in dedicated subtitle editors like Subtitle Edit and Aegisub. Because it's plain text, it also opens in Notepad or TextEdit, though it will display raw timecodes rather than a preview.
Why does SRT have no styling or colors?
SRT was designed as a byproduct of ripping DVD subtitles to text, not as a typesetting format, so it only ever recorded a timecode and the caption line. That simplicity is why every player reads it; formats like ASS exist specifically to add styling back in.
Does an SRT file break if the video's frame rate changes?
No. SRT times each caption by clock time, in hours:minutes:seconds,milliseconds, so it stays in sync no matter what frame rate the video plays at. That's different from a frame-based format like MicroDVD SUB, which times captions by frame number and drifts out of sync if the frame rate doesn't match.
What's the difference between SRT and VTT?
SRT is plain numbered captions with no styling, while WebVTT is the W3C's version of the same idea built for HTML5 video, adding cue positioning and CSS-style formatting. The two are close enough that converting SRT to VTT is a near-lossless, mostly mechanical change.
Can I add bold or italic text to an SRT file?
Some players accept HTML-style tags like <b>, <i> and <font color> inside an SRT caption, but this was never standardized, so support varies by player and the tags are stripped or shown literally in others. A format built for styling, such as ASS, is the reliable way to control text appearance.
Converting SRT files#
Convert SRT to another format
Convert another format to SRT
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.