Subtitle reading speed
Characters per second, spaces and punctuation included.
Check whether a subtitle sits within reading-speed limits: one cue, or a whole file — SRT, WebVTT, YouTube SBV, TTML / EBU-TT-D, EBU-STL or Scenarist SCC — dropped in and scanned for the fastest lines. Every character a viewer reads is counted, spaces and punctuation included, with a cue’s lines joined by one space.
Reading speed = characters ÷ seconds on screen, counting the whole cue (all lines joined with one space, spaces and punctuation included). Words-per-minute is shown alongside for reference.
CPS vs WPM
Characters per second (CPS) is the metric most subtitle specs enforce and the one this tool judges against. It’s language-agnostic and maps directly to on-screen text. The ceilings here are generic: 17 CPS is a common cautious figure for adult programmes, 13 for young children. Every delivery spec sets its own. Words per minute (WPM), the BBC’s traditional measure (roughly 160–180 wpm), is shown alongside for reference, but words vary in length, so CPS is the tighter test. Always defer to the commissioning spec.
How the count works
A cue’s lines are joined with a single space and measured whole (spaces and punctuation included, exactly as a viewer reads it) then divided by the seconds the cue is on screen. Formatting tags (<i>, override blocks) aren’t counted, since a viewer doesn’t read them; untick “strip tags” to count them as written.
Captioning YouTube videos? The YouTube version is simpler and built for creators. Related: safe areas & caption cages · timecode calculator · subtitle fixer & converter.