Yoast keyphrase length: why four content words is the target
Yoast SEO's Keyphrase length check counts the content words in the focus keyphrase you typed into the sidebar. One to four content words is green, five to eight is orange, and more than eight is red. If you leave the field empty, the check goes red and Yoast cannot calculate your SEO score at all.
The length of this field has no direct effect on Google, because the keyphrase is never shown to search engines. What it changes is how every other keyphrase check in Yoast grades your post.
How the words are counted
Yoast counts content words, the words that carry meaning, and skips function words such as "for", "the", "with" and "how" in languages where it has function word lists. So waterproof trail running shoes for wide feet has six content words (waterproof, trail, running, shoes, wide, feet) and lands in orange, even though "for" is also in the phrase.
For languages without function word support, every word counts and the bands shift up: one to six words is green, seven to nine is orange, and more than nine is red. Japanese is measured in characters instead, with 12 characters as the upper end of green.
The feedback reads like this when you go over: "The keyphrase contains 6 content words. That's more than the recommended maximum of 4 content words. Make it shorter!" A related grey notice, Function words in keyphrase, appears if you type a phrase made only of function words, for example "how to", because there is nothing left to match.
The real reason for the limit: matching
The rule makes most sense once you see how Yoast matches keyphrases elsewhere. Several checks need all of the content words to appear together:
- Keyphrase density only counts a match when every content word appears in the same sentence.
- Keyphrase in introduction wants all the content words in one sentence of the first paragraph for green.
- Keyphrase in SEO title gives its best result to an exact match at the start of the title.
With three content words, that is easy to satisfy in natural sentences. With nine, it is close to impossible without writing the whole phrase out word for word again and again. The length check is partly there to stop you from setting a keyphrase that the rest of the analysis cannot reasonably find.
The other reason is editorial. A keyphrase is meant to be the search your page answers, and most searchers type a short core phrase plus a few modifiers. Pasting an entire question into the field usually means the page has not settled on its main topic yet.
Why length is invisible to search engines
The focus keyphrase lives in your WordPress database as a Yoast setting. It is not printed in your page's HTML, and Google stopped using the old meta keywords tag for web ranking long ago. Nothing about the length of this field reaches a search engine.
So there is no ranking reason to shorten it. The only reason is practical: a well-chosen, short keyphrase makes Yoast's other feedback useful, while an overlong one turns half the panel orange for reasons that have nothing to do with your writing.
Long-tail searches still matter, of course. A page can and should answer a specific, multi-word need. The point is that the specific need goes in your headings, your intro and your answer, while the keyphrase field holds the core of it. See long-tail keywords for how that fits together.
Picking a keyphrase that works
A few rules of thumb:
- Find the core noun phrase. For a post answering "how long should cold brew steep in the fridge", the core is
cold brew steeping time(four content words). - Say it out loud. If you would not use the phrase in a sentence, the matching checks will force awkward copy.
- Keep modifiers for the title and headings. "In the fridge", "for beginners" or a year can sit in the SEO title without being part of the keyphrase.
- Check it against your other posts. Yoast's previously used keyphrase check will warn you if you have targeted it before.
Orange is acceptable when the phrase is inherently long, such as a full product name, a legal term or a place name with several parts. Accept that the density and title checks will be harder to satisfy, and do not rewrite good sentences just to repeat a five-word name.
Focus keywords in Hydrogen SEO
Hydrogen SEO also has a focus keyword field in the SEO Settings sheet, and it feeds one fifth of the post's SEO score. There is no separate length check, but length matters in the same way: the score counts how often the exact phrase appears in the text, ignoring case. A long phrase that never appears word for word scores zero for that part, however well the post covers the topic.
If you switch from Yoast, the importer brings each post's focus keyphrase across; see switch from another SEO plugin.
Common questions
Is a longer focus keyphrase better for long-tail SEO?
No. The keyphrase field is only used by the plugin's own checks. Target long-tail searches through your headings and content, and keep the field to the core phrase so the other checks can match it.
Why does Yoast say my three-word keyphrase has two content words?
One of the words is on Yoast's function word list for your language, so it is not counted. That is expected and does not affect how well your post can rank.
What happens if I leave the keyphrase empty?
The keyphrase length check goes red and the keyphrase-based checks cannot run, so Yoast cannot give you an SEO score. Readability analysis still works without a keyphrase.