We have an enough old but still supported website which is XHTML 1.0 Transitional now. We are going to change it to HTML 5 to add some new features in the future (microdata, <header>/<footer> tags, etc).

At the moment, we are planning just change the doctype to <!doctype html> and do some polishing to make our website fully compatible with HTML 5 standard. How can this doctype change affect our SERP positions and other things related to SEO?

1 Answer 1


Just changing from XHTML to HTML 5 won't be an issue or make a difference. If you change your markup you will affect your rankings as semantic markup is a ranking factor. So if your markup is different it stands to reason your rankings may be different.

No one can say if it will be helpful or harmful as we have no idea what changes you will be making or if they will be done well, etc. But if you mark up your content properly you should be ok.

The microdata shouldn't affect your rankings but should make your listings in the search results richer for any supported formats such as recipes, breadcrumbs, etc.


Updating the doctype will have no effect on rankings. The doctype of the page is not a ranking factor.

  • I wanted to ask whether just changing the doctype to HTML5 would affect SERP positions. Sure, special works like writing microdata, wrapping the corresponding parts with special tags like <header> are the future works. I'll correct the question accordingly right now.
    – TecMan
    Jan 31, 2014 at 14:09

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