How to use Subtitle Quality Checker
- Paste SRT or WebVTT and select the matching Input format.
- Set the duration, reading-speed, line-length and line-count thresholds for your review.
- Run the checker and inspect the cue numbers and issue descriptions in its report.
- Edit the source separately and check it again; this tool does not rewrite or synchronise subtitles.
Example: Subtitle Quality Checker
Find a brief cue that overlaps the preceding caption.
Options
- Subtitle text
- Paste SRT or WebVTT, up to 1 MiB and 5,000 cues. This checker reports issues without rewriting or syncing cues.
- Minimum cue seconds
- Cues shorter than this threshold receive a duration finding. It is a chosen review rule, not a universal accessibility standard.
- Maximum cue seconds
- Cues longer than this value receive a separate duration finding. Choose it for the kind of captions you are checking.
- Maximum characters per second
- Characters divided by cue duration estimate reading load. This count is not language-aware and does not establish whether a real reader can follow the caption.
- Maximum characters per line
- Checks each stored line against a character count. Font, display width and actual rendered wrapping are not measured.
- Maximum lines per cue
- Counts line breaks in a cue. A player can wrap text differently, so review the captions on the intended screen.
Supported inputs and limits
Where your input is processed
This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.
A finding starts a review rather than deciding quality
Overlap may be deliberate for simultaneous speakers, while a short cue can be difficult to read. The checker identifies structural conditions under your thresholds. It cannot judge translation, speech accuracy, speaker identity or visual placement. Read the flagged cue in context before changing it.
Use the same timing basis when checking a revision
The report uses subtitle timestamps as supplied; it does not compare them with a video clock. If captions drift progressively, a simple threshold change will not solve the synchronisation problem. Correct the source timing using the actual media, then rerun the checker to inspect the resulting cues.
Questions about Subtitle Quality Checker
Will the subtitles be fixed?
No. The tool produces a report so you can choose the edits.
Does characters per second measure actual reading difficulty?
No. It is a simple threshold and does not understand language or context.
Can it check sync with a video?
No. It checks the entered subtitle timings without opening media.