Subtitle CPS Checker
Measures reading speed (characters per second) for every cue in SRT and VTT files. Runs in your browser.
How it works
Drop an .srt or .vtt file and every cue is listed with its number, start time, character count, duration and characters per second. Click any column heading to sort by it, which is the fastest way to find the worst offenders: sort by cps descending and the lines nobody can read are at the top.
How characters are counted
Whitespace and markup tags are stripped before counting, so a two-line cue is not penalised for its line break and italic tags do not inflate the number. Duration comes from the cue’s own timecodes. A cue with no duration shows a dash instead of an absurd rate, because dividing by zero is not a reading speed.
Thresholds
Two presets are built in: 21 characters per second for adult programming and 17 for children’s, both from Netflix’s published timed-text specification. They are guides, not laws — a repeated line, a name, or a number reads far faster than prose at the same character count, and a good subtitler overrides the meter when the content justifies it.
Export and privacy
Export CSV writes the whole table out for a spreadsheet or a QA report, generated in the browser from data that was already in the browser. Nothing is uploaded at any point, which matters because reading-speed passes usually happen on material still under embargo.