Pillar pages and topic clusters: what to build, and how to tell if it worked

What is a pillar page?

A pillar page is a page that covers a broad topic in one place and links to more specific pages, called cluster pages, that each go deep on one part of it. Each cluster page links back to the pillar. Together, the pillar and its cluster pages form a topic cluster. HubSpot, which popularised the model, describes a pillar page as a comprehensive resource on a topic, and Ahrefs’ glossary describes it as the main page on a topic, targeting the most popular keyword in the cluster.

This guide is about planning and judging the structure. The detailed link rules for every content type are in the internal linking strategy guide, and the Topical Map Generator drafts clusters and pillars from your own keyword list.

Pillar pages, topic clusters and subtopics: the terms

The vocabulary varies between tools and agencies, but the parts are the same. The table uses the terms as they are used in this guide.

Term	What it is	Example for a project management product
Topic	A subject your customers care about, broad enough to need several pages	Project planning
Pillar page	The page that covers the topic broadly and links to every cluster page	A guide to project planning
Cluster page	A page that answers one narrower question within the topic, and links back to the pillar	How to write a project scope statement
Topic cluster	The pillar and all its cluster pages, linked together	The project planning guide and its twelve supporting posts
Hub page	A pillar written as an organised index, with short summaries of each cluster page	A project planning resource library

Two terms need care. HubSpot’s own documentation calls the cluster pages subtopics and notes that creating topic clusters in its tool does not affect your website’s SEO directly: the tool organises your planning, and the effect comes from the pages and links you build. And older guides use cornerstone content for much the same idea. The label matters less than the rule that each page has one job.

Do pillar pages and topic clusters work?

The honest answer is that the structure helps, but not for the reasons usually given, and the case studies prove less than they claim. It helps because building a cluster forces three things that do affect search: one page per search intent, duplicate pages merged, and internal links that tell search engines how pages relate.

What the evidence shows

The best-known case is HubSpot’s own. Its account of moving its blogs to the pillar and cluster model describes grouping posts into topics broad enough for 20 to 30 posts each, merging duplicate posts into the highest-ranking URL with redirects, removing and rebuilding internal links, and redesigning the blog. It reports month-over-month growth in page-one keywords but gives no figures, and since consolidation, redirects, relinking and a redesign all happened together, the result cannot be credited to the cluster structure alone. A 2018 Content Marketing Institute article cites a HubSpot test showing more internal links led to higher placement, again without numbers.

Google’s documentation supports the parts, not the label. Its link best practices say every page you care about should have a link from at least one other page on your site, and the SEO starter guide says the vast majority of new pages Google finds are found through links, and recommends organising a site so its structure makes sense. Its guidance on helpful content asks whether your site has a primary purpose or focus, and whether you are producing lots of content on many different topics in the hope some of it performs.

That is also why clusters fit the wider point of the SEO audit guide: the gains come from fixing the system that produces pages, so each new page has a place, a target and links before it is written, rather than from a one-off clean-up. What the structure is meant to produce, being treated as a reliable source on the whole subject, is the subject of the guide to topical authority.

Two kinds of pillar page: the guide and the hub

Pillar pages come in two forms, and the choice depends on what the results page for the broad query rewards. A guide pillar answers the broad query itself, in depth. A hub pillar is an organised index that summarises each part and sends the reader to the cluster page that covers it.

Guide pillar

Strengths

• Answers the broad query on one page, so it can rank for it on its own content
• Suits topics where searchers want an overview they can read straight through

Limits

• Long, and the easiest kind of page to make overlap with its own cluster posts
• Needs a firm rule on how deep each section goes before it hands off to a cluster page

Use it when the top results for the broad query are long overviews.

Hub pillar

Strengths

• Short sections that summarise and link, so overlap with cluster pages is small
• Easy to keep current: a new cluster page is one new entry

Limits

• Ranks for the broad query only if searchers want a map of the topic rather than an answer
• Weak if the summaries are so short they add nothing

Use it when the top results are resource libraries, category pages or curated lists.

Most B2B topics suit a guide pillar with a firm depth rule: each section answers the question in two or three paragraphs and then links to the cluster page that covers it fully. That rule is what stops the pillar from becoming a long page that competes with every post beneath it.

How to decide what is a pillar and what is a cluster page

Search intent decides it. A query whose results page rewards broad overviews is a pillar query. A query whose results page rewards one specific answer is a cluster query. Two queries whose results pages share most of the same URLs belong on one page, whichever role it plays.

The results-page test is the one used in the keyword cannibalization guide: search both queries and compare the top ten organic results. My working rule is that four or more shared URLs means one page. Word overlap is the faster first pass, and the Topical Map Generator applies it to a whole keyword list, then the results-page check settles the pairs that word overlap gets wrong. The methods and thresholds are compared in the keyword clustering guide.

Do the top ten results for this query mostly cover a whole subject, rather than one task or question?

Yes, mostly overviews

Is there already a page on your site that ranks for this query, or for one that shares four or more top-ten URLs with it?

Yes

Make that page the pillar. Expand it to cover the topic and link to the cluster pages, rather than writing a second overview.

No

This is a new pillar. Write it after you have mapped at least five or six cluster pages, so it has something to link to.

No, mostly specific answers

Does it share four or more top-ten URLs with a query you already target?

Yes

Merge it into that page as a section or a variant. It is the same intent, so a second page would compete with the first.

No

It is a cluster page. Assign it to the pillar whose topic it belongs to, and give it its own target query.

The four-URL threshold is a working rule, not a published standard. Pick a threshold and apply it the same way every time

Two more checks keep the map sane. A pillar topic should be broad enough for several cluster pages; HubSpot grouped topics broad enough for 20 to 30 posts, but a smaller site can start with six. And it should be something your product helps with, because the pillar is where readers of every cluster page arrive, and that is where the link to the commercial page belongs.

How to build a topic cluster, step by step

A topic cluster is built from a keyword map, not from a list of post ideas. The order below puts the decisions that are expensive to change, the targets and the merges, before the writing.

1. 1InventoryList every existing URL on the topic with the queries it ranks for, from Search Console.
2. 2CollectExport the keyword list for the topic from your keyword tool, with volume and difficulty.
3. 3GroupCluster the keywords by results-page overlap into one row per intent, and assign each row one URL.
4. 4ChooseMark the row with the broadest intent as the pillar, and the rest as cluster pages.
5. 5MergeWhere two existing pages sit in one row, merge them into the stronger URL with a redirect.
6. 6FillWrite the missing cluster pages first, then the pillar, or expand the existing pillar.
7. 7LinkPillar to every cluster page, every cluster page back to the pillar, and a few links between siblings.
8. 8MeasureRecord the cluster’s clicks and ranking queries before you start, and compare monthly.

The Topical Map Generator does the grouping, choosing and link planning steps from an exported keyword list, and maps the clusters to your existing pages so you can see where the merges are. For a site where the existing structure is unclear, start with a content audit, which settles which pages to keep, merge, rewrite or remove before you build anything on top of them.

What goes on a pillar page

A pillar page has one job: to be the best single page for the broad query and the clearest route to every part of the topic. The elements below serve one or both halves of that job.

Element	Why it is there	Rule
A direct definition or answer	The broad query deserves an answer in the opening paragraph	Answer in two or three sentences before any background
Contents list	Readers of a long page jump to the part they need	One entry per section, linked to the section
A section per cluster page	This is where the pillar covers the topic broadly	Two or three paragraphs, then a link to the cluster page
Descriptive links to each cluster page	Readers and search engines learn what each page covers	Anchor text that says what the target page is about
A link to the commercial page	Readers from every cluster page arrive here	Where the topic meets what you sell, not in every section
Visible updates	The pillar is the page most likely to go stale as the cluster grows	A new section and link every time a cluster page ships

Length follows from the topic, not from a target. Older guides set pillars at 3,000-plus words; Google’s helpful content guidance asks whether you are writing to a particular word count because you have heard Google prefers one, and says it does not. The depth rule sets the length: as many sections as the topic has parts, each short enough to hand off.

Keep the pillar crawlable and open. HubSpot’s guidance is that a pillar page should not put its content behind a form, and should sit at the top level of the site where it gets traffic. A gated pillar can be read by neither the people you want nor the crawler.

How to link a topic cluster

A topic cluster is linked as a hub with some mesh: the pillar links to every cluster page, every cluster page links back to the pillar, and cluster pages link to two or three siblings where a reader of one would want the next. Chains, where each page links only to the next, suit ordered courses and little else.

Filled node is the pillar. Most clusters work best as a hub with a few mesh links between related cluster pages

Three rules matter more than the rest. First, the link from a cluster page to the pillar goes in the body, early, in a sentence where it makes sense, not only in a footer. Second, anchor text describes the target: Google’s link best practices ask for anchor text that is descriptive, reasonably concise and relevant, and give generic phrases such as click here and read more as bad examples. Third, every cluster page gets a link from the pillar, because Google’s same guidance is that every page you care about should have a link from at least one other page.

The full rules for each content type, including how many links and where, are in the internal linking strategy guide. To check a cluster once it is linked, the Internal Link Mapper reads a crawl export and shows click depth, orphans and which pages receive the most internal link authority.

Topic cluster calculator: links and effort

Before committing to a cluster, it helps to see the size of the job. Enter how many cluster pages the topic needs, how many already exist, and how many sibling links each page should carry. The calculator counts the links to build and how long publishing the missing pages takes at your pace.

Hypothetical defaults. Change them to your own topic and pace.

Cluster pages the topic needsCluster pages that already existSibling links per cluster pageNew pages you can publish a monthMinutes to add one link to a live pageminutes

Cluster pages to write

8

Links in the finished cluster

48

Pillar to each page, each page back, plus sibling links

Links to add to pages already live

16

Assumes the existing pages are not linked as a cluster yet

Hours to retrofit the live pages

2.7

Months to publish the missing pages

4.0 months

Months until most pages have had a year to mature

16.0 months

New pages often take a year or more to reach steady traffic

Links into new pages are written as each page is published, so only the existing pages need a retrofit. The maturity figure is a rough planning horizon, not a forecast.

The last line is the one to show whoever approves the work. A twelve-page cluster at two pages a month takes four months to publish and the better part of two years to judge fairly. Setting that expectation at the start is easier than defending a flat graph in month three. For forecasting the traffic itself, see the SEO forecasting guide.

When the pillar competes with its own cluster pages

The most common failure in a topic cluster is the pillar ranking for its cluster pages’ queries, or a cluster page ranking for the pillar’s, so that two of your own pages trade places for one query. It happens because a guide pillar covers every subtopic, and a section that grows past a summary becomes a second answer.

Not every overlap is a problem. Ahrefs’ guide to keyword cannibalization argues that Google does not get confused by several pages on similar subjects, and that it is a real issue only when pages target the same keyword and organic performance suffers. A pillar ranking at position six for a long-tail query its cluster page ranks third for is normal. Two pages swapping in and out of position eight for the cluster page’s main query is not.

What you see in Search Console	What it means	What to do
The pillar gets a few impressions for a cluster page’s query, well below it	Normal: the pillar mentions the subtopic	Nothing
The pillar and a cluster page alternate for the cluster page’s main query	The pillar’s section has become a second answer	Cut the section to a summary and link to the cluster page with a descriptive anchor
A cluster page ranks for the broad query instead of the pillar	The cluster page is the better broad answer, or the pillar is weak	Strengthen the pillar’s opening answer, or make the cluster page the pillar
Two cluster pages alternate for one query	Two pages share one intent	Merge them into the stronger URL and redirect the other

The detection method, a Search Console query report filtered to one query with the Pages tab compared over time, is set out step by step in the keyword cannibalization guide, along with how to merge two pages without losing traffic.

Pillar pages and AI search

Topic clusters suit AI search for a specific, documented reason. Google’s guide to AI features says AI Overviews and AI Mode may use a technique called query fan-out, issuing multiple related searches across subtopics and data sources to build a response. A cluster that answers each subtopic on its own page gives each of those searches a page that matches it.

The same guide also limits what to expect. It says there are no additional requirements to appear in AI Overviews or AI Mode, and no special optimisations necessary, and among the fundamentals it lists making content easily findable through internal links. A topic cluster is ordinary good structure, and that is the claim to make for it, not that it is an AI tactic.

Write each cluster page so the answer can stand on its own: the question in the heading, a direct answer in the first paragraph, and the detail after. How AI systems retrieve and use passages from a page is covered in the guide to what AI search actually retrieves, and the wider work of tracking and improving AI visibility is the subject of the AI search visibility service.

How to measure a topic cluster

Measure a cluster as one unit, because its pages share traffic and their rankings move together. Looking at the pillar alone undercounts the result, and looking at each post alone hides the overlaps.

1

Define the cluster

List every URL in the cluster. If they share a folder, a page filter on that folder covers them; otherwise use a custom regex page filter listing them.

2

Take the baseline

Before publishing or relinking, record the cluster’s monthly clicks, impressions and number of queries with impressions, for the previous twelve months if you have them.

3

Track the cluster total

Each month, compare the cluster’s clicks and ranking queries with the same months a year earlier, to allow for seasonality.

4

Watch the pillar’s share

Check which page takes the clicks for the broad query and for each cluster query. A cluster page taking the broad query, or the pillar taking a cluster query, is the overlap problem.

5

Judge at the right time

Give new pages a year or more before calling the cluster a success or a failure.

The order and timings are a working method, not a measured standard

Three numbers are worth reporting: the cluster’s clicks against the same period a year earlier, the number of queries the cluster ranks for in the top ten, and the conversions from readers who entered on a cluster page. The last needs the analytics side to be working; when attribution undercounts organic search, as it usually does, the approach in SEO measurement when attribution is already broken applies.

A worked example: turning 40 posts into three clusters

Take a hypothetical B2B software company with 40 blog posts written over three years, no pillars, and links added whenever an author remembered. The numbers below are invented to show the method; the steps are the point.

Measure	Before	After
Blog posts	40	34 posts plus 3 pillars
Pairs of posts targeting one intent	6	0, after merging 6 posts into others
Posts with no link from another post	11	0
Posts linking to a commercial page	9	34, through the pillar or directly
Posts not in any cluster	40	4, kept as standalone pieces

Hypothetical figures to show the method

The work ran in the order of the flow above. An inventory from Search Console showed six pairs of posts trading places for one query; each pair was merged into the stronger URL with a redirect. Clustering the remaining posts’ queries by results-page overlap gave three topics with eight to fourteen posts each. Two topics already had a broad post that could be expanded into a guide pillar, and one needed a new pillar, written last. Every post then got a link up to its pillar in the first third of the body and two sibling links, and each pillar got a section and a link for every post.

What the company could expect, and when, is the subject of the calculator above: the merges and links are a few days of work, while the new pillar and any new cluster pages need a year or more to be judged.

Common pillar page and topic cluster mistakes

Most cluster mistakes are planning mistakes that only show up months later in Search Console. Each item below comes with the check that catches it.

• The pillar written as a long post that answers everything. Check: does each section hand off to a cluster page within two or three paragraphs?
• A pillar with nothing to link to. Check: are at least five or six cluster pages mapped before the pillar is written?
• Two pages for one intent. Check: does every row in the keyword map have exactly one URL?
• Topics chosen by what the team wants to write. Check: does every pillar query have search demand and a results page that rewards overviews?
• Links only in a related posts box. Check: does every cluster page link to the pillar in the body, early?
• Generic anchors. Check: would the anchor text alone tell you what the target page covers?
• A gated pillar. Check: can the full pillar be read without a form?
• No commercial link. Check: does the pillar link to the page where the topic meets what you sell?
• Judged on the pillar alone, in month three. Check: is the cluster measured as one unit against a baseline, over a year?

Plan

Keywords grouped by results-page overlap, one row per intent One URL per row, with existing duplicates merged and redirected One pillar per topic, chosen because its results page rewards overviews At least five or six cluster pages mapped before the pillar is written

Build

Pillar answers the broad query in its opening paragraph Each pillar section summarises, then links to its cluster page Every cluster page links to the pillar in the body, early Descriptive anchor text on every link in the cluster Pillar is ungated and links to the relevant commercial page

Measure

Cluster URLs saved as a Search Console page filter Baseline recorded before the work started Pillar and cluster pages checked monthly for overlap on their main queries

Ticks are saved in your browser.

Building clusters across a whole site, with templates, link rules and a keyword map that every new brief is checked against, is the core of an SEO systems engagement.