The short answer
Use SRT when a platform asks for a subtitle file and doesn't say which kind: it's the most widely accepted format. Use VTT for video on your own website, because browsers' built-in video player reads WebVTT. Converting one to the other takes a second with the free subtitle converter.
What each file looks like
An SRT file is numbered blocks: a counter, a time range, then the text, with a blank line between blocks. Times use a comma before the milliseconds, like 00:00:01,250 --> 00:00:03,000.
A VTT file starts with the line WEBVTT. The blocks don't need numbers, and times use a full stop: 00:00:01.250 --> 00:00:03.000. After the time range a VTT cue can carry settings such as position and alignment, and the file can include styling and notes.
The differences that matter
| SRT | VTT (WebVTT) | |
|---|---|---|
| First line | The first cue's number | WEBVTT |
| Milliseconds separator | Comma (,) | Full stop (.) |
| Cue numbers | Required | Optional |
| Position and alignment | No standard way | Cue settings |
| Styling | Basic tags in some players | CSS styling in browsers |
| Plays in the HTML5 video player | No | Yes, through a <track> element |
Which one to use where
- YouTube: SRT or VTT, both accepted.
- Facebook and LinkedIn videos: SRT.
- Your own website: VTT, for the browser's video player.
- Video editors: SRT is the most common import format.
- Instagram Reels and TikTok: neither; captions have to be in the video. See burned-in vs closed captions.
Common subtitle file problems
- Strange characters (é instead of é): the file isn't saved as UTF-8. Save or export it as UTF-8 and upload again.
- Every line early or late by the same amount: the video was trimmed after the subtitles were made. Shift all the timestamps with the subtitle timing fixer.
- Lines drifting further out of step over time: the subtitles were made for a different frame rate or edit. Stretch the timings, or re-transcribe the final video.
- Two lines on screen at once: cues overlap. Each cue should end before the next begins.
- Lines too long to read: a common subtitling guideline is about 42 characters per line and two lines at most.
Other subtitle formats you may meet
| Format | What it is | Where you see it |
|---|---|---|
| SBV | A simple plain-text format | Older YouTube caption downloads |
| ASS / SSA | Subtitles with fonts, colours, positions and effects | Fan subtitles, desktop video players |
| TTML / DFXP | An XML subtitle format | Broadcast and some streaming platforms |
| TXT | The words only, no timing | Transcripts, show notes, blog posts |
For social video, SRT and VTT cover nearly every case; CAPWAV gives you both, plus a plain TXT transcript.
Converting and fixing subtitle files
The subtitle converter turns SRT into VTT and VTT into SRT in your browser, free, with no sign-up and nothing uploaded. If your subtitles are early or late against the video, the subtitle timing fixer shifts or stretches every timestamp at once.
Don't have a subtitle file yet? Transcribe your video with CAPWAV and download SRT, VTT or TXT, free on every plan.