What an SRT file is and why you need one

An SRT file is a plain text document that holds subtitles for video. SRT stands for SubRip, a format that video players recognize natively — meaning you can drop an SRT file next to your video file and most players will find it automatically. The file contains only text, timecodes, and sequence numbers, nothing else. You can create one in any text editor: Notepad on Windows, TextEdit on Mac, or gedit on Linux.

Video platforms like YouTube, Vimeo, and many streaming services accept SRT files for captions. If you're uploading video to any of those places, or sharing video files locally and want subtitles to travel with them, an SRT file is the simplest format to use. It's also the easiest format to edit by hand if you need to adjust timing or wording later.

Key Takeaways

  • An SRT file is a text document with three parts per subtitle: a sequence number, a timecode showing when the text appears and disappears, and the subtitle text itself.
  • You can create an SRT file in any text editor by typing the format manually, or use free subtitle software like Aegisub or Subtitle Edit to time subtitles to your video automatically.
  • Each subtitle block must be separated by a blank line, and timecodes must follow the exact format HH:MM:SS,mmm (hours, minutes, seconds, milliseconds).
  • Save the file with a .srt extension in the same folder as your video, and most players will load it without extra steps.

The structure of an SRT file

Every subtitle in an SRT file follows the same three-line pattern. The first line is a number — 1, 2, 3, and so on — that marks the order of subtitles. The second line is the timecode: when the subtitle appears and when it disappears, separated by an arrow. The third line (or lines, if the subtitle is long) is the actual text.

Here's what a real example looks like:

1 00:00:05,000 --> 00:00:08,500 Welcome to the tutorial. 2 00:00:09,000 --> 00:00:12,300 Today we're learning how to edit video. 3 00:00:13,500 --> 00:00:18,000 This process takes practice, but you'll get faster over time.

The timecode format is always HH:MM:SS,mmm — hours, minutes, seconds, and milliseconds separated by a comma (not a period). The arrow between start and end time must have spaces around it: --> with a space before and after. Between each subtitle block, you must have one completely blank line. If you skip the blank line, the player may not read the file correctly.

Creating an SRT file by hand in a text editor

Open Notepad (Windows), TextEdit (Mac), or any plain text editor. Do not use Word or Google Docs — those add invisible formatting that breaks SRT files. Type your subtitles following the three-line pattern above, making sure each block is separated by a blank line.

The hardest part of hand-typing an SRT file is getting the timecodes right. You'll need to watch your video and note exactly when each subtitle should start and stop. Pause the video at the moment a speaker begins talking, check the timestamp, and write it down. Then find where that sentence ends and write down that timestamp too. This is slow and error-prone, which is why most people use subtitle software instead.

Once you've typed all your subtitles, go to File > Save As. Name the file something clear — for example, if your video is called "tutorial.mp4", name the SRT file "tutorial.srt". The filename before the dot should match your video filename exactly, and the extension must be .srt. Save it in the same folder as your video file. When you open the video in a player that supports SRT files, the subtitles should load automatically.

Using subtitle software to time subtitles automatically

Aegisub and Subtitle Edit are free programs that let you play your video, type subtitles, and set their timing by clicking buttons or using keyboard shortcuts. This is much faster than hand-timing. Both programs run on Windows, Mac, and Linux.

In Aegisub, you open your video file, and the video plays in a window while you type subtitles in a grid below. You click a button to mark when a subtitle starts, type the text, click again to mark when it ends, and move to the next one. The software keeps track of the timecodes for you. When you're done, you export the file as SRT.

Subtitle Edit works similarly but with a slightly different layout. Both programs let you adjust timing after the fact if a subtitle is off by a few frames, and both can import subtitles from other formats if you're converting from something else. If you're creating subtitles from scratch, either tool will save you hours compared to hand-timing.

Uploading SRT files to video platforms

YouTube accepts SRT files directly. Go to your video's details page, click Subtitles, and choose to add subtitles manually or upload a file. If you upload a file, select your SRT file and YouTube will read the timecodes and text automatically. You can then edit any subtitle in YouTube's editor if the timing is slightly off.

Vimeo, Wistia, and most other video hosting platforms have similar upload options. Look for a Subtitles or Captions section in your video settings. The process is usually: click Add Subtitles, choose Upload, select your SRT file, and confirm. The platform reads the file and displays subtitles in the player.

Some platforms require you to specify a language when you upload. If your SRT file is in English, select English. If you have multiple language versions, upload each one separately and the platform will let viewers choose which language they want to see.

Common mistakes and how to fix them

The most common mistake is saving the file with the wrong extension. Make sure it ends in .srt, not .txt or .doc. If you created the file in Notepad and it saved as "tutorial.txt", rename it to "tutorial.srt" before using it.

The second most common mistake is incorrect timecode format. The format must be HH:MM:SS,mmm with a comma before milliseconds, not a period. If you write 00:00:05.000 instead of 00:00:05,000, some players will reject the file. Also check that the arrow between start and end time has spaces: --> not --> or -->.

If subtitles don't appear when you play your video, check that the SRT file is in the same folder as the video and has the same filename (except for the extension). If the video is "lesson.mp4", the SRT must be "lesson.srt". Some players require this exact match to auto-load subtitles. If the file is in a different folder or has a different name, you may need to manually select the subtitle file in the player's menu.

Converting subtitles from other formats to SRT

If you have subtitles in another format — VTT, ASS, SUB — you can convert them to SRT using Subtitle Edit or an online converter. In Subtitle Edit, open the file you want to convert, then go to File > Save As and choose SubRip (.srt) from the format dropdown. The software will rewrite the file in SRT format while keeping all the timecodes and text.

Online converters like CloudConvert or Subtitle Tools let you upload a subtitle file and read it in a different format. These work for quick one-off conversions, but if you're converting many files, installing Subtitle Edit is faster. Be aware that some subtitle formats support styling (bold, color, positioning) that SRT does not, so you may lose that information in the conversion.

Frequently Asked Questions

Can I use Microsoft Word to create an SRT file?

No. Word adds hidden formatting that breaks SRT files. Use Notepad, TextEdit, or a code editor instead. If you've already typed subtitles in Word, copy all the text, paste it into Notepad, and save that as .srt.

What if my video player doesn't show subtitles even though the SRT file is in the same folder?

Some players don't auto-load SRT files. Try opening the player's menu and looking for a Subtitles or Captions option, then manually select the SRT file. If that doesn't work, the player may not support SRT at all — try VLC Media Player instead, which reads SRT files reliably.

How do I know if my timecodes are accurate?

Play the video in a player that supports your SRT file and watch the subtitles. If a subtitle appears before the speaker starts talking or disappears before they finish, the timing is off. Open the SRT file in Subtitle Edit, adjust the timecode for that subtitle, save, and test again.

Can I have multiple subtitles on screen at the same time?

SRT format doesn't support overlapping subtitles — each subtitle replaces the previous one. If you need multiple lines of text on screen simultaneously, you'll need a more advanced format like ASS. For most videos, one subtitle at a time is standard.

What's the maximum length of a subtitle line?

There's no hard limit, but most players display about 42 characters per line before wrapping. Keep subtitles to two lines maximum for readability. If your subtitle is longer, break it into two separate subtitle blocks with slightly overlapping timecodes.