Subtitle reading speed
Characters per second, the way QC counts them.
Check whether a subtitle sits within reading-speed limits: one cue, or a whole file — SRT, WebVTT, TTML / EBU-TT-D, EBU-STL or Scenarist SCC — dropped in and scanned for the fastest lines. The character count matches SpectraQC’s QC exactly, so a “comfortable” here is a pass there.
Reading speed = characters ÷ seconds on screen, counting the whole cue (all lines joined, spaces and punctuation included), the same count SpectraQC’s QC uses, so this and a real check agree. 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. Netflix’s English timed-text guideline is 17 CPS for adult content and around 13for children’s; many EBU-based broadcaster specs land in a similar range. 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. That’s the same calculation SpectraQC’s reading-speed check runs, so results line up. Formatting tags (<i>, override blocks) are counted as-is unless you tick “strip tags”.
SpectraQC runs full subtitle QC across SRT, WebVTT, TTML/IMSC and EBU-TT-D: reading speed, gaps, overlaps, line length. See the subtitle checks.