YouTube description length checker

YouTube allows 5,000 characters and shows about the first 150 before "Show more". Everything that has to be read — the link, the offer, the summary — belongs in those 150.

The fold is brutal and almost nobody expands. That makes the first two lines the entire practical description for most viewers, and the remaining 4,850 characters a place for chapters, links, credits and disclosures rather than persuasion. Chapter timestamps are the exception worth the effort: putting `0:00` at the start of a properly formatted timestamp list creates chapter markers on the progress bar, which measurably helps retention on longer videos. Note that links in a description are not clickable until the channel is verified.