YouTube's exact chapter requirements
YouTube only turns timestamps in a description into clickable chapters when a few specific rules are met: the first chapter must start at exactly 0:00, there must be at least 3 chapters, each chapter must be at least 10 seconds long, and timestamps must be in ascending order with a consistent format. This tool reformats whatever you paste into that exact format and flags anything that would stop YouTube from recognizing the chapters.
Paste the result directly into your video's description, exactly as formatted.
Why the first-chapter-at-0:00 rule exists and why it's non-negotiable
YouTube uses the first timestamp to anchor the entire chapter structure - without a 0:00 starting point, there's no defined reference for where the video's first segment begins, which is why YouTube treats this as an all-or-nothing requirement: chapters won't display at all if it's missing, regardless of how correctly every other timestamp is formatted.
Why chapters need to be sorted before checking any of the other rules
Checking rules like "is the first chapter at 0:00" or "are chapters at least 10 seconds apart" only makes sense against chapters in their actual chronological order - running those checks on an out-of-order paste would flag the wrong entry as the problem, which is why this tool sorts by timestamp first and validates everything else against that corrected order.
Why the minimum chapter count and spacing rules exist
YouTube requires at least 3 chapters because fewer than that doesn't meaningfully function as navigation, and chapters closer than 10 seconds apart would create entries too brief to represent a meaningful segment of the video - both are practical floors below which the chapter feature stops adding real navigational value for a viewer.