What Is an SRT File? Format, How to Open and Create One
What is an SRT file?
An SRT (SubRip Subtitle) file is one of the most widely used plain-text subtitle formats for video. The extension is ".srt". Inside, it contains only three things, repeated: a sequence number that sets each subtitle's order, timecodes that set when the text appears and disappears, and the subtitle text itself. Because it's plain text, you can open and read an SRT file with nothing more than the text editor built into your OS.
Here's what the contents actually look like:
1
00:00:01,000 --> 00:00:04,000
Hello — today we're talking about SRT files.
2
00:00:04,500 --> 00:00:07,200
Plain text you can open in Notepad.
SRT files are supported by YouTube, VLC, Windows Media Player, Adobe Premiere, and most other major platforms and editing tools. "Simple, and it works everywhere" — that's why SRT remains the default subtitle format.
Inside an SRT file: the 4 components
Each subtitle block in an SRT file consists of four parts:
1. Line number Indicates the subtitle's position in the sequence.
2. Timecodes
Specifies the start and end times for the subtitle in the form 00:01:23,456 --> 00:01:25,789. A distinctive SRT quirk: the millisecond separator is a comma, not a period.
3. Subtitle text The text displayed on the screen — usually one or two lines.
4. An empty line Separates each subtitle entry for clarity.
How to open an SRT file (3 ways)
1. Using a text editor
Since SRT files are plain text, you can open them with any default text editor pre-installed in your OS — Notepad on Windows, TextEdit on Mac. That's plenty for checking the contents or fixing typos. You can even edit timecodes by hand, but adjusting timing to the millisecond by eye isn't realistic.
2. Using subtitle editing software
SRT is supported by numerous free and paid subtitle editing tools, such as Subtitle Edit and Aegisub. The difference from a text editor: you can adjust timing and sync while previewing against the video. If your goal is to actually edit an existing subtitle file, this is the way.
3. Using a media player (to display it)
Most media players, such as VLC and Windows Media Player, can display SRT subtitles. Place the SRT file in the same folder as the video file (matching filenames make it reliable), play the video, and the subtitles show automatically. You can't read or edit the file's contents as text this way, but it's the easiest method to check finished subtitles on the video.
How to create an SRT file
There are two ways to make one:
- Write it by hand: type the structure above into a text editor and you already have a valid SRT file. Realistic only for videos of a few minutes at most — matching timecodes by ear and eye gets painful fast as the video gets longer.
- Generate it with AI: upload your video or audio to an AI transcription tool like Subanana and it generates a timecoded SRT automatically. It supports 80+ languages, and after generation you can fix proper nouns and adjust timing in the browser editor before exporting the SRT. It can also export translated subtitle files alongside the original.
Why use SRT files?
1. Universal compatibility
Supported by platforms like YouTube and Vimeo, and media players like VLC and Windows Media Player.
2. Ease of use
Simple text-based format that's easy to create and edit.
3. Lightweight
Small file size, making it easy to share and store.
4. Customizability
Allows precise timing adjustments and text edits, even without dedicated software.
Best practices for working with SRT files
1. Check encoding
Use UTF-8 encoding to support special characters and multiple languages — it's the most common cause of garbled subtitle text.
2. Test subtitles
Preview subtitles in a media player to ensure accurate timing and text display.
3. Back up files
Save a copy of the original SRT file before making edits.
4. Use consistent formatting
Maintain uniform font sizes and styles when supported by the platform.
5. Validate timestamps
Ensure timestamps don't overlap to avoid subtitle conflicts.
Summary
An SRT file is a simple plain-text subtitle format built from sequence numbers, timecodes, and subtitle text. To read one, a text editor is enough; to check the result on video, use a media player; to edit, use subtitle editing software — pick the method by what you're trying to do. And if you're creating one from scratch, AI generation is far more practical than writing timecodes by hand.