How to use it
- Open the .srt or .vtt file in a text editor, copy everything and paste it into the box.
- Choose the reading speed limit from your style guide.
- The box on the right lists every subtitle over the limit with its number, timecodes, speed and the count of characters and seconds. Choose “All subtitles” to see every line.
- Fix the fast lines by shortening the text or giving it more time on screen, then paste again to check.
How it works
For each subtitle block the tool reads the line with “–>”, the start and end times (HH:MM:SS,mmm in SRT, HH:MM:SS.mmm or MM:SS.mmm in WebVTT) and the text lines below it.
CPS = characters ÷ (end − start in seconds)
Tags such as <i>, <b>, <font> and {\an8} are removed before counting, and two lines count as one text without the break. A subtitle with no duration is shown as ∞. The figure for the whole file is all characters divided by all display time.
Worked example
The sample has three subtitles:
- “Where were you last night?”: 26 characters in 2.5 s = 10.4 CPS;
- “I told you, I was at work until late.”: 37 characters in 1.4 s = 26.4 CPS, over 17;
- “Nobody believed him.”: 20 characters in 2.8 s = 7.1 CPS (the italic tags do not count).
The summary reads: 1 of 3 subtitles is over 17 CPS, the fastest is 26.4 CPS, and the whole file averages 83 ÷ 6.7 = 12.4 CPS.
Tips
- A fast subtitle can often borrow time from a gap before or after it; keep the minimum gap your guide asks for between subtitles.
- Very short subtitles on screen for under a second are hard to read even with few characters.
- Shorter wording is usually better than squeezing time: cut filler words and repeated names.