What is an SRT file?
Four lines of plain text, repeated. That is the entire format.
SubRip Subtitle files — .srt — are the most widely accepted subtitle format in the world, and the reason is that there is almost nothing to them. They came out of a Windows program for ripping subtitles off DVDs in the late nineties, and they won by being simple enough that every player, platform and editor could support them without thinking about it.
Open the subtitle editor → Opens the editor. Use "Open an SRT or VTT" to look inside a file you already have.- 100% freeNo account, no minute quota, no paid tier.
- Nothing is uploadedYour video is read on your device and never reaches a server.
- No catch on the outputNo watermark, no length cap, no locked export formats.
- Updated in the openEvery fix is written down on the changelog page.
The structure
A subtitle file is a list of blocks separated by blank lines. Each block has a sequence number on its own line, a timing line with a start time, an arrow and an end time, and then one or two lines of text:
1 / 00:00:02,350 --> 00:00:05,180 / Hello everyone. / (blank line) / 2 / 00:00:05,400 --> 00:00:08,000 / Welcome back to the channel.
Timestamps are hours, minutes, seconds and milliseconds, always two digits for the first three, three for the milliseconds, and — the detail that catches people — a comma before the milliseconds, not a period. Blocks must be in chronological order and numbered from one. That is the whole specification. There is no styling, no positioning, no speaker field and no metadata.
How to open one
To read it, any text editor will do: Notepad, TextEdit, VS Code. It is plain text, and looking inside is the fastest way to understand what a subtitle file actually is.
To edit it usefully, you want it next to the video, because the hard part is never the words — it is the timings, and counting milliseconds in a text editor is miserable. Open it here with Open an SRT or VTT, add the video, and the file becomes a list you can click through with an audio waveform underneath it.
To watch with it, name the file exactly like the video file — movie.mp4 and movie.srt in the same folder — and VLC, mpv and most desktop players will load it automatically.
The three things that break SRT files
Encoding. SRT has no declared character set, so a file saved as Windows-1252 or Big5 and opened by something expecting UTF-8 produces question marks, boxes or mojibake. Always save as UTF-8. This is the single most common cause of a platform rejecting a file without explaining why.
Numbering. The sequence must start at one and increase without gaps. Hand-editing a file and deleting a block leaves a hole that strict parsers reject. Lenient parsers — including this one — accept it, but the platform you are uploading to may not.
Overlaps. Nothing in the format forbids one block starting before the previous one ends, and some players will show both at once, stacked on top of each other. Fixing overlaps is part of what the auto-format button does.
SRT versus the alternatives
WebVTT is the web's version, with a header line, periods instead of commas, and real support for positioning and styling. Browsers require it — an HTML5 video element will not accept SRT. Converting SRT to VTT is lossless.
ASS/SSA is the format used for fansubbing and karaoke, with a full styling engine: fonts, colours, outlines, positioning, animation. It can do things SRT cannot dream of, and almost no platform accepts it.
SRT survives because it is the lowest common denominator, and in subtitle distribution that is a feature. If you are choosing one format to hold, hold SRT.
Frequently asked questions
Can I edit an SRT in Notepad?
Yes, it is plain text. Save as UTF-8 or you will get mojibake. Editing timings by hand is the painful part, which is what an editor with a video and a waveform is for.
Comma or period before the milliseconds?
Comma in SRT, period in VTT. That difference alone will make a parser reject the file.
Can an SRT position text or change its colour?
No. It has no styling or positioning at all. VTT and ASS do.
Why does my SRT show strange characters?
Almost always encoding. Re-save it as UTF-8. Opening and re-exporting it here does that for you.