YouTube chapter rules
Chapters split a video into sections, each with its own preview, which makes it easy for viewers to find and rewatch different parts. YouTube builds them from the timestamps in your description, but only when the list meets three rules from its help center:
- The first timestamp is 00:00.
- There are at least three timestamps, in ascending order.
- Every chapter is at least 10 seconds long.
Manual chapters vs. automatic chapters
YouTube can also create automatic chapters for eligible videos, though not every eligible video gets them. Chapters you add yourself override the automatic ones. If you'd rather YouTube never adds them, uncheck Allow automatic chapters in a video's settings, or in Upload defaults to change it for future uploads.
Some channels can't use chapters at all. YouTube says the feature isn't available when a channel has active strikes or when the content may be inappropriate for some viewers, and channels without access are pointed to apply for advanced features.
What this timestamp generator checks
It checks the format of every line, sorts the lines by time, and writes each time in a consistent mm:ss or h:mm:ss style. It warns you when the first chapter isn't at 00:00 and when you have fewer than three chapters.
It flags any two timestamps less than 10 seconds apart, including duplicates. It never sees your video, though, so it can't tell how long the video is: make sure the last timestamp falls at least 10 seconds before the end.