SRT Caption Guide: Subtitle Formats, Timing, and Accessibility
5 min read · Updated June 2026
Captions are no longer optional — YouTube, Netflix, and most social platforms require them for accessibility. Whether you're a YouTuber, course creator, or filmmaker, understanding subtitle formats and timing is essential.
Common Subtitle Formats
| Format | Platform | Notes |
|---|---|---|
| SRT | YouTube, VLC, most players | Most widely supported |
| VTT (WebVTT) | HTML5 video, web players | Like SRT with CSS styling support |
| TXT (plain text) | Transcripts, AI tools | No timing info — needs conversion |
SRT Format Structure
1
00:00:01,000 --> 00:00:04,000
Hello, welcome to this video.
2
00:00:04,500 --> 00:00:07,000
Today we'll learn about captions.
Characters Per Second (CPS)
CPS measures reading speed. If captions appear too fast, viewers can't read them:
- 15 CPS — Comfortable for most viewers
- 17 CPS — Maximum recommended
- 20+ CPS — Too fast — split into two lines or extend duration
Common Issues and Fixes
- Timing drift — Apply a time offset to shift all captions forward or back
- Long lines — Wrap at 42 characters per line, max 2 lines
- Format conversion — SRT ↔ VTT conversion is straightforward
- Auto-generated errors — YouTube's auto-captions often have timing and accuracy issues
💬 Format and fix Your Captions
Use our SRT Caption Formatter to convert between SRT/VTT/TXT, apply time offsets, wrap long lines, and check CPS — auto-detects format.
The Bottom Line
- SRT is the most universal subtitle format
- Keep CPS under 17 for readable captions
- Max 2 lines, 42 characters per line
- Always check auto-generated captions for timing and accuracy errors
Disclaimer: This guide is for informational purposes only.