YouTube title, description and tag counters

The counters

Three fields, three units, one page. The title and the tag list are counted in characters. The description is counted in UTF-8 bytes, because that is the unit YouTube writes down, and a character counter will quietly let a description through that the API rejects.

Where the text is cut off

The YouTube pages read on 2026-10-08 state no character count at which a description is truncated by the "more" control. The description counter therefore measures length against the documented byte maximum and does not claim a fold position.

The description limit is bytes, and that changes real drafts

A byte limit and a character limit are the same number only while every character is one byte, which is true for ASCII and false for almost every caption anyone writes in a language other than English.

Each row below is computed from the same inputs the counter uses: the string, the UTF-8 encoding, and the 5,000 byte budget.

The woman technologist row is the one worth remembering. It reads as a single emoji on every platform, and it costs 11 bytes against a 5,000 byte budget. 454 of them fill it. That number is computed: 5,000 divided by 11, rounded down.

The tag limit counts commas and quotation marks

YouTube documents the tag limit in two extra sentences that a plain comma-joined string length will not match. Verbatim: "Note the following rules regarding the way the character limit is calculated:" "The property value is a list, and commas between items in the list count toward the limit." "If a tag contains a space, the API server handles the tag value as though it were wrapped in quotation marks, and the quotation marks count toward the character limit."

YouTube gives its own worked example in the same paragraph: "So, for the purposes of character limits, the tag Foo-Baz contains seven characters, but the tag Foo Baz contains nine characters."

The tags counter applies both rules and nothing else. Split a tag list on commas, add the length of each tag in characters, add two for each tag that contains a space, then add one comma for every gap between items.

That last step is why a list of 250 tags in the shape Foo Baz does not fit in 500 characters even though a character count of the joined string would say it does. It is computed the way YouTube counts: each tag is 7 characters plus 2 quotation marks, so 250 tags are 250 times 9, which is 2,250, plus 249 commas between the items, which is 2,499 characters against a 500 character maximum.

What the reference says about which characters are allowed

Both the title and the description carry the same clause: the value "may contain all valid UTF-8 characters except < and >". Two characters are excluded, and the reference excludes them by naming them rather than by stripping them.

The title field also carries an extra condition: "You must set a value for this property if you call the videos.update method and are updating the snippet part of a video resource." That is about the update call rather than about length, but it explains why an update that clears a title behaves the way it does.

Frequently asked questions

Sources

1. YouTube Data API: Videos resource (snippet.title, snippet.description, snippet.tags) (checked 2026-10-08)

Every figure on this page is quoted from the platform document named above, with the date it was read. Where those pages state no limit, this page states none and says so, rather than filling the gap with a figure from somewhere else.

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