Free tool
Caption CPS calculator
Check how fast a caption reads before you publish. Enter the text and the time it is on screen; the calculator returns characters per second and average line length.
Reading speed
0 CPS
Characters
0
Average chars / line
0
Verdict
Waiting for text
CPS is a heuristic, not a rule. Around 15–20 CPS is a common target for adult audiences; children, dense terminology and second-language viewers may need slower captions.
Why CPS matters
Captions are read, not listened to. A line can be accurate and still be unreadable because it appears for too little time. CPS gives you a quick check; then confirm the line breaks and the smallest text size on a phone-sized preview.
Questions
What is a good CPS for captions?
Around 15–20 characters per second is a common target for adult audiences. Children, dense terminology and second-language viewers may need slower captions.
What about characters per line?
A common guideline is 32–42 characters per line for broadcast-style captions, and fewer characters on vertical video. The right number depends on font size and screen.
Does CPS guarantee readability?
No. It is a useful heuristic. Line breaks, punctuation, contrast, safe-zone placement and the viewer’s language all affect readability.