Why heading structure matters
Headings are the outline of a page. Screen-reader users jump between them to navigate; search engines use them to understand topics and sections; and every reader uses them to skim. A good structure has:
- One H1 that states what the page is about.
- H2s for the main sections and H3s for subsections inside them, without skipping levels (an H4 directly after an H2 suggests a missing level).
- No empty headings and no headings used purely for visual styling.
- Distinct wording: duplicate headings make navigation confusing.
Using the checker
Paste a page’s HTML source or a Markdown document. The tool detects the format, extracts every heading (HTML <h1>–<h6>, Markdown # and underline-style headings, ignoring code blocks), and draws the outline with indentation by level. Problems are listed underneath.
Multiple H1s are valid HTML and Google has said they are not a ranking problem in themselves, but a single, clear H1 remains best practice for accessibility and clarity. Skipped levels are flagged because the Web Content Accessibility Guidelines (WCAG) expect headings to convey the structure of the content.
Worked example
Here is what the Heading Structure Checker returns for its built-in example. Settings used: Input is: Auto-detect. Click Try an example in the tool above to load it, then change it as you like.
<h1>Complete Guide to Readability</h1>
<h2>What readability means</h2>
<h4>Flesch Reading Ease</h4>
<h2>How to improve it</h2>
<h3>Shorter sentences</h3>
<h3></h3>
<h1>Another H1</h1>| Result | Value |
|---|---|
| Headings | 7 |
| H1 | 2 |
| H2 | 2 |
| H3–H6 | 3 |
| Issues | 3 |
| Format | HTML |
Questions
Can a page have more than one H1?
Technically yes, but one H1 that describes the page is clearer for readers and assistive technology.
Is it bad to skip heading levels?
It confuses the document outline, especially for screen-reader users. Go from H2 to H3, not straight to H4.
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