Developer & Digital Tools · 🌏 Global
YouTube Chapter Timestamp Formatter
Convert free-form timestamps into YouTube chapter format and validate the 5 YouTube rules in real time.
About this tool
YouTube Chapter Timestamp Formatter takes free-form chapter notes and converts them to YouTube's recognized chapter format (first chapter 0:00, ≥3 chapters, ≥10-second gaps, ascending order, mm:ss or hh:mm:ss, one chapter per line). It checks all 8 rules and surfaces the exact rule that fails, plus warnings for truncation risk and excessive intervals. Output goes straight into the video description. No YouTube API call — input never leaves the browser. Bilingual KO / EN, useful for both Korean and global channels.
Use cases
Scenario 1
Auto-fix missing 0:00
When chapter 1 starts at 0:15 (and chapters won't render), get the exact reason and apply the 0:00 fix before copying out.
Scenario 2
Sub-10-second warning
Enter 8-sec gaps and the tool warns red — "this chapter is dropped and merged into the next".
Scenario 3
Long video → hh:mm:ss
For a 1 h 5 min video where chapters were written as mm:ss, auto-convert to hh:mm:ss.
Scenario 4
Title truncation check
Titles over the desktop ~40 / mobile ~25-char limit get a yellow warning.
Scenario 5
Korean / emoji width check
Mixed Korean + emoji titles get pixel-accurate width checks.
Features
- 8 YouTube chapter rules auto-validated
- 0:00 start / ≥3 / ≥10 sec gaps / ascending
- Auto mm:ss / hh:mm:ss conversion
- Yellow warnings for truncation-risk titles
- Copy button → paste straight into description
- Bilingual KO / EN + fully in-browser
Frequently asked
- Q. Most common reason chapters don't render?
- A. 80%+ are (1) first chapter not at 0:00 or (2) second chapter within 10 seconds of the first. The tool checks these first.
- Q. 0:00 or 00:00?
- A. Both work. Under 1 hr → mm:ss; 1+ hr → hh:mm:ss; the tool converts automatically.
- Q. Title-length limit?
- A. No hard limit, but desktop ~40 / mobile ~25 chars truncate (about half for Korean). The tool warns at the truncation point.
- Q. Korean / emoji in titles?
- A. All allowed — Korean / Japanese / Chinese / emoji / symbols. Some emojis (flags / family) have wider grapheme widths.
- Q. Does the tool insert chapters for me?
- A. No. It only validates and formats text; no YouTube API call. Paste the result into your description.
Sources / references
Related guides / blog posts
Related tools
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How we run it / disclaimer
This tool is advisory and does not constitute legal, tax, medical, or financial advice. All calculations and document generation run in your browser; inputs are never sent to a server. Ads follow Google AdSense policy and are kept separate from tool accuracy.