Glossary
What is a timestamp?
By the KeyMo team · Updated
A timestamp marks a point in a recording by how far in it is, written as minutes and seconds like 12:34, or hours, minutes and seconds like 1:02:15. In video it lets you link to, chapter or cut a moment. In logs and databases, a timestamp can instead mean a date and time.
Timestamp formats you will see
| Format | Example | Where it appears |
|---|---|---|
| mm:ss | 12:34 | Chapter lists, descriptions, show notes |
| h:mm:ss | 1:02:15 | Episodes longer than an hour |
| Whole seconds | 3735 | The start setting for an embedded YouTube player |
| hh:mm:ss.mmm | 01:02:15.000 | WebVTT caption files, with a full stop before the milliseconds |
| hh:mm:ss,mmm | 01:02:15,000 | SRT caption files as shown in YouTube's example, with a comma |
To convert 1:02:15 to seconds, multiply hours by 3600 and minutes by 60, then add: 3600 + 120 + 15 = 3735. Minutes and seconds never go past 59.
Linking to a moment
On YouTube, the Share panel has a Start at box. Tick it, enter a time such as 2:30 for two minutes thirty seconds, and the copied link opens there. For embedded players, the start setting is a whole number of seconds, and YouTube says the player seeks to the nearest keyframe, so playback can begin up to around two seconds early.
Timestamps also drive chapters. YouTube's rules are: the first timestamp must be 00:00, there must be at least three, they must be in ascending order, and each chapter must last at least 10 seconds.
Using timestamps to find clips
Suppose an editor notes a strong 40-second answer at 41:10 to 41:50 in a one-hour episode. Start a second or two before 41:10 so the first word is not clipped, and end after the last word has landed. A transcript with timestamps turns that from a scrub through audio into a search for a phrase.
Common mistakes
- Writing 41.10 or 41-10 when the tool expects 41:10.
- Using a comma where WebVTT wants a full stop, or the reverse in SRT. See SRT and VTT for the differences.
- Cutting exactly on a timestamp. Speech starts a beat before the word you noted.
- Forgetting that a video's displayed time can shift after trimming.
Where KeyMo touches it
You do not need to log timestamps by hand to use KeyMo. It reads a source of 5 minutes to 3 hours and picks the moments, returning vertical clips of 15 to 90 seconds. If you want to change a clip, open it and tell the chat editor what to adjust.
Sources: YouTube Help, Share a video (Start at) (checked 11 October 2026); YouTube IFrame Player API, player parameters (checked 11 October 2026); YouTube Help, Video chapters (checked 11 October 2026); W3C, WebVTT: The Web Video Text Tracks Format (checked 11 October 2026); YouTube Help, Supported caption file formats (checked 11 October 2026).