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Subtitle Quality Checker

Check subtitles against broadcast standards for reading speed, line length and duration.

Subtitle quality standards exist because unreadable subtitles are worse than none. This checker tests reading speed in characters per second, characters per line, lines per cue, minimum and maximum duration, overlapping cues and gaps too small to register — against the values the BBC and Netflix publish.

Runs in your browser
Checks
Reading speed, line length, line count, duration, overlaps, gaps and empty cues
Based on
BBC Subtitle Guidelines and the Netflix Timed Text Style Guide
Privacy
Runs entirely in your browser — nothing is uploaded
Cost
Free, unlimited, no sign-up

Frequently asked questions

Why does reading speed matter more than character count?

Because a long line held for six seconds is comfortable while a short one flashed for half a second is not. Characters per second captures the relationship between the two, which is what a viewer actually experiences.

How to use the subtitle quality checker

  1. 1Enter or paste your subtitle file.
  2. 2Set the maximum reading speed.
  3. 3Set the maximum characters per line.
  4. 4Set the maximum lines per cue.
  5. 5Set the minimum cue duration.
  6. 6The result appears immediately — copy or download it.

Embed this tool

Put the working subtitle quality checker on your own site. It runs in your visitors' browsers exactly as it does here — free, no account, nothing uploaded.

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