Free tool · runs in your browser

Caption Line Splitter

Enforce broadcast-style caption rules: at most 2 lines per cue and 42 characters per line. Cues that exceed the limit are split into multiple cues with timing divided proportionally by character count, so the rhythm of the original transcript is preserved.

Split SRT output

// Paste an SRT file above to enforce broadcast caption rules.

How to use this tool

  1. 01

    Upload or paste your SRT

    The input cues may have lines over 42 characters or too many lines per cue.

  2. 02

    Run the splitter

    Adjust the limits if needed; the summary reports how many cues exceed them and the new total.

  3. 03

    Download the corrected SRT

    Re-verify on the video — automatic splits may need light cleanup at sentence boundaries.

Why this matters

Auto-generated captions and AI transcripts routinely produce single cues with five or more lines that flash on and off far too fast to read. Accessibility standards cap captions at two lines of about 42 characters because that's the limit at which a viewer can actually finish reading before the next cue — over-long cues are present but effectively useless.

Splitting cues by hand means recalculating timing for every break, which is tedious and easy to get wrong. This tool divides each over-long cue's duration proportionally so the total caption time is preserved exactly, and runs entirely in your browser. The output is SRT; if you need WebVTT for an HTML5 player, run it through the SRT to VTT Converter.

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FAQ

These limits come from accessibility standards (the US FCC closed-captioning rules, BBC and EBU subtitle guidelines) and are backed by readability research on how fast people read on screen. Past roughly 42 characters per line or more than two lines, a cue can't be read before it's replaced — so over-long captions are effectively unusable even though they're technically present.

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