CapsAI

Caption readability check

Subtitle Reading Speed Checker

Estimate how much reading each subtitle asks viewers to do during its screen time. Review characters per second and words per minute cue by cue, with a configurable CPS threshold.

Browser-basedFree to use

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Tool workspace

No account required · processed locally

17 CPS is a practical review starting point, not a universal rule.

Three steps

How this tool works

  1. 1

    Add a valid SRT subtitle track.

  2. 2

    Set the characters-per-second limit.

  3. 3

    Review cues that need more time or shorter text.

Useful for

Common workflows

  • Accessibility review
  • Fast-paced Shorts captions
  • Course and explainer subtitles

What it checks

Focused, transparent output

  • Characters per second
  • Words per minute
  • Cue-level threshold flags

Questions

Frequently asked questions

What is CPS in subtitles?

Characters per second divides visible non-space characters by the cue duration.

What CPS limit should I use?

Standards vary by audience and platform. Start around 17 CPS, then account for language, age and content complexity.

Why can a short caption still be too fast?

A small amount of text can be difficult to read when the cue appears only briefly.

Continue your subtitle workflow

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