SUBTITLE REFERENCE DESK
Subtitle reading-speed calculator
Check characters per second, words per minute and line length before your captions reach the screen.
How it works
Characters per second = grapheme count ÷ duration in seconds. Words per minute = word count × 60 ÷ duration. Line breaks do not count as characters; spaces do. Words use the browser’s language-aware segmentation.
Worked example
“Hello world” over 2 seconds: 11 characters, 2 words, 5.5 CPS and 60 WPM. Arabic combining marks and emoji sequences count as visible graphemes where Intl.Segmenter is available.
Useful limits
These are measurements, not an accessibility or broadcaster certification. Reading targets vary by language, age and delivery specification. Segmentation depends on your browser’s Unicode version.
Unicode Text Segmentation · Reviewed 2026-10-04 · Licenses