What they did
Backlinko counted the words on pages ranking on the first page of Google across its 11.8 million result sample and averaged them.
What they found
The average first-page result came in at 1,447 words.
How much weight to give it
An average word count across all queries tells you little about any single search. Longer content correlating with page-one rankings does not mean word count is the driver. Depth that genuinely answers the query is the plausible link, and word count is just a rough shadow of that.
What it doesn't prove
Intent varies wildly by query, so a single average flattens navigational, transactional and informational searches together. Do not read 1,447 as a target to hit.