Subtitle Reading Speed (CPS) Analyser

How to use the Subtitle Reading Speed Checker

1. Drop a subtitle file or paste its text.
2. Set the limits for your platform: max characters per second (17 for children, 20 for adults), max characters per line (42 is typical), minimum and maximum duration.
3. Optionally tick List only subtitles with issues to focus on problem cues.
4. Click Analyse reading speed, read the summary and download the CSV report for editors or translators.

What the numbers mean

• CPS (characters per second) is the number of visible characters divided by the cue’s duration. Spaces are counted, tags are not.
• Line length is the longest line in the cue. Lines above the limit are hard to read or wrap awkwardly.
• Duration is end minus start. Very short cues flash; very long cues linger after the speech ends.

Typical limits

These values are based on widely published streaming-service style guides. Always check your own platform’s current requirements.

How to fix cues that are too fast

1. Edit the text to be shorter without losing the meaning.
2. Extend the cue’s end time into silence if the next cue starts later.
3. Start the cue earlier if the speaker begins before the subtitle appears.
4. Split a long sentence into two cues with their own timings.

The CSV report

The report lists every cue with start, end, duration, characters, CPS, longest line, number of lines and flags (fast, short, long, wide, overlap). Open it in Excel or Google Sheets to sort by CPS or send it to the translator.

A worked example

Take the cue “I never said that you couldn’t come with us.” It is 48 characters including spaces. Shown for 2.0 seconds, it reads at 24 CPS — too fast for adults. Extending it to 2.5 seconds gives 19.2 CPS, which passes. If the next cue starts too soon to extend, shorten the text instead: “I never said you couldn’t come.” (31 characters) at 2.0 seconds is 15.5 CPS. This is exactly the trade-off the report highlights.

Frequently asked questions