There’s no universal length, and you don’t decide it; the query and the SERP do. “Fully answer” doesn’t mean hitting a word target you set in advance. It means resolving every real sub-question the searcher still has when they land, and the right length is simply however many words that takes, no more and no less. So the ruler is not your house template. It is the query itself, and the live results page is where you read it.

Two places tell you what “fully” requires for a given query. The first is the top-ranking results. The depth, format, and coverage Google is already rewarding show you the baseline the query expects: a string of short, direct answers means the query is simple, while a field of detailed guides means it wants depth. Your job is not to match their word count but to cover at least what they cover and then add something better. The second is People Also Ask and related searches. Those are the searcher’s follow-up questions laid out in the open, the sub-questions a complete answer has to close. When your page resolves the main question and the genuine follow-ups the SERP reveals, it has fully answered the query, and whatever length that took is the right length. Padding past that point or stopping short of it both miss the mark.

This is why a fixed house word count is the wrong starting place. It sizes the page to your habit instead of to the searcher’s actual questions.

Before writing, pull the live SERP for the query. Read what the top results genuinely cover and what People Also Ask is asking, and let that set the depth of your page. The query hands you the list of questions; your length is just the space it takes to answer all of them and nothing it didn’t ask.