H1 Tags: Why One Per Page Still Matters
Use exactly one H1 per page stating what the page is about. HTML5 permits multiple H1s inside sectioning elements, but no major browser or screen reader implements the outline algorithm that would make them meaningful — so in practice multiple H1s just blur what the page is about.
The rule, and the exception people cite
One H1 per page, stating the page's subject. That's it.
The objection you'll hear is that HTML5 introduced a document outline
algorithm where each <section> establishes its own heading
context, making multiple H1s valid. That's true of the specification. It is not
true of any shipping implementation — the outline algorithm was never
implemented by browsers or assistive technology, and the W3C guidance moved back
to recommending a single H1.
So the spec-lawyer position is correct and useless. In the world where your pages are actually read, one H1 is the working rule.
Why a missing H1 is worse than a duplicate one
In this product's severity model, no H1 is high severity while multiple H1s is medium. The gap is deliberate.
A page with several H1s is ambiguous but still says something. A page with no H1 forces engines to infer the subject from the title tag, anchor text, or whatever heading appears first — and it strands screen reader users who navigate by heading level.
Missing H1s are usually template bugs rather than editorial choices. A theme that renders the site name as an H1 on the homepage and nothing on interior pages is a classic. Which means one fix repairs hundreds of pages.
See this on your own site. isaeo audits up to 10 pages free — no card, no trial timer. You get an SEO health score, an AEO score and a prioritised fix list.
Run a free audit →Getting hierarchy right
Headings are an outline, not a styling menu. The pattern:
- H1 — the page subject. One, near the top.
- H2 — major sections. Make these question-shaped where it fits naturally.
- H3 — subsections within an H2.
- H4+ — rarely needed. If you're at H5, the page probably wants splitting.
Don't skip levels going down — an H4 directly under an H1 breaks the outline for anyone navigating by structure. Skipping back up is fine: H3 followed by the next H2 is normal.
And don't pick heading levels for their font size. If your H2 is too big, that is a CSS problem with a CSS solution.
Fixing it at template level
Crawl the site and count H1s per page. You'll almost always find the pattern clusters by template — all blog posts fine, all product pages missing, or the logo wrapped in an H1 site-wide.
Fix the template, re-crawl, and confirm the count went to one everywhere. This is the kind of change worth verifying with a diff against the previous crawl, because template edits have a habit of fixing one page type and breaking another.
Try it on a site you care about
isaeo reports missing and duplicate H1s per page, so template-level heading bugs show up as a cluster you can fix once.
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Frequently asked questions
Can a page have more than one H1?
HTML5 technically allows it inside sectioning elements, but the document outline algorithm that would give it meaning was never implemented by browsers or screen readers. Use one H1 per page in practice.
Is a missing H1 an SEO problem?
Yes, and a more serious one than having several. Without an H1, search engines infer the page's topic from weaker signals and screen reader users lose the primary landmark for navigating the page.
Should the H1 match the title tag?
They can be the same, but differing usefully is common: the title targets search phrasing and competes in the results page, while the H1 confirms to an arriving reader that they're in the right place.