What is an SRT file? Anatomy, editing and common errors

The short answer

An SRT file is a plain-text subtitle file. It lists numbered captions, each with a start time, an end time and one or two lines of text, and almost every video player, TV, editor and video platform can read it.

The name comes from SubRip, a Windows program that read subtitles from DVDs and saved them as text. SRT never had an official specification, so what counts as valid is mostly what popular players accept. That is good news when you edit one by hand: the format is simple and forgiving.

The parts of a caption

Every caption, sometimes called a cue or a subtitle block, has four parts. The first line is a counter: 1 for the first caption, 2 for the next and so on. The second line is the timing, written as hours, minutes, seconds and milliseconds, with a comma before the milliseconds and an arrow made of two hyphens and a greater-than sign between the start and the end. Then come the lines of text, usually one or two. A blank line ends the caption.

Times are counted from the start of the video. 00:01:02,500 means one minute, two and a half seconds in. Most players hide the caption at the end time, so two captions should not overlap unless you want both on screen at once.

1
00:00:01,200 --> 00:00:03,900
Is anyone here?

2
00:00:04,300 --> 00:00:06,800
MAYA: Over here.
<i>Follow my voice.</i>

Formatting you can use

SRT has no official styling, but most players understand a few HTML-like tags: <i> for italics, <b> for bold and <u> for underline. Italics are the most common, for voices from off screen, phone calls, song lyrics and foreign words. Some players also show <font color="..."> tags, and some files carry ASS position codes such as {\an8} to put a caption at the top.

Support varies. Some platforms, YouTube among them, ignore all markup in SRT files. The tools on this site keep italic, bold and underline. They remove font color tags and ASS position codes, because many players would otherwise show them as text.

How to open and edit an SRT file

Any plain-text editor works: Notepad on Windows, TextEdit on a Mac in plain text mode, or a code editor. Avoid word processors such as Word, which can add hidden formatting or curly quotes when you save. When you save, choose UTF-8 as the encoding so every letter shows correctly in modern players.

For small fixes, such as a typo or a missing line, a text editor is all you need. For timing changes across the whole file, editing hundreds of timestamps by hand is slow and error-prone; the subtitle time shifter moves every caption at once. A dedicated subtitle editor is better when you need to re-time captions one by one against the audio.

Common SRT errors and how to fix them

When a player refuses an SRT file or shows it wrong, the cause is usually one of the following. The tools on this site are tolerant of several of them, so opening a damaged file in the converter and downloading it as SRT again often repairs it in one step.

• A dot instead of a comma before the milliseconds, as in 00:00:01.200. Strict players reject this. The converter reads it and writes a comma.
• Missing blank lines between captions. Some players merge the captions. The converter still separates them, because it starts a new caption at every timing line.
• Numbers that skip or repeat. Players rarely care, but some editors do. Every SRT file the tools write is numbered again from 1.
• An end time before the start time, or a negative time. Those captions are skipped, and the page tells you how many blocks could not be read.
• Overlapping captions, where one is still on screen when the next starts. The subtitle cleaner can end each caption when the next one begins, and the subtitle checker lists every overlap.
• Strange characters instead of accented letters. That is an encoding problem; the page lets you pick the right encoding and saves the result as UTF-8.
• Times missing the hours, as in 01:02,500, or short fractions, as in 00:00:01,5. The converter reads both and writes full times.

Where SRT files come from

You are most likely to get an SRT file from a subtitle download site, from a video editor or transcription service that exports captions, or from a video platform where you can download the captions of your own videos. Subtitle editors save SRT by default, and many programs that pull subtitle tracks out of MKV or MP4 files save text tracks as SRT too.

Files from download sites vary a lot in quality. They may have been made for a different release of the video, saved in an old regional encoding, or filled with credits and web addresses. Before you rely on one, play a few scenes from the start, middle and end of the video to check that the timing holds.

Naming an SRT file so players find it

Players and TVs usually load an SRT file automatically when it sits next to the video and has the same name, such as holiday.mp4 and holiday.srt. Many also understand a language code before the extension, so holiday.en.srt and holiday.es.srt appear as English and Spanish. Some players recognize extra labels such as sdh or forced, for example holiday.en.sdh.srt, but support differs, so check your player if the label does not show.

What the tools on this site do with an SRT file

Every tool here reads SRT, and each one leaves the original file untouched; you download a new file. The converter writes it in another format. The subtitle time shifter moves or stretches every timing. The subtitle cleaner removes sound descriptions, speaker names, repeated captions and credits. The subtitle checker lists captions that are too fast, too long or overlapping. The merger, splitter and subtitle to text tool join, cut or transcribe files.

All of them run in your browser, and the file is not uploaded. Every file they save is UTF-8 and keeps italic, bold and underline where the output format allows.

SRT compared with other formats

SRT's strength is that everything reads it. Its weaknesses are the lack of a specification and of real styling. WebVTT is nearly identical but is a web standard, and it is the only format browsers show natively. ASS adds fonts, colors and placement. If a platform or player asks for something other than SRT, the converter can write VTT, ASS, SBV, TTML, DFXP, SAMI, MicroDVD SUB, LRC, CSV, Spruce STL or plain text from the same file.

Common questions

Is an SRT file the same as a video with subtitles? No. It is a separate text file that a player shows on top of the video. The subtitles can be turned off, changed or fixed without touching the video.

Can one SRT file hold two languages? Not as separate tracks, but each caption can contain a line in each language. The subtitle merger can combine two files that way.

Can I open an SRT file on a phone? Yes. Any text viewer can show it, and the tools on this site work in a phone browser.