In this Google Webmaster's answer, it is stated that one of the cons of specifying a canonical link is that it "can add to the size of the page".

I tried searching the web for more information on that topic but most articles I found were quite old and even then there was no mention of an increase in page size due to usage of canonical link.

Does the author refer to the nominal increase in the page's size due to the extra few lines in the markup? The wording makes it seem the impact is greater than that.

  • 3
    It adds very little... just a few bytes... nothing to write home about. May 15, 2018 at 13:31
  • Maybe it is very big compared to issuing a redirect? Redirect responses are very small while canonical tags are embedded in a full page. May 15, 2018 at 13:35
  • Hmm.. But the help document says that the canonical header doesn't add to the page size. It does add to the response size. May 15, 2018 at 13:37

2 Answers 2


The sole purpose of the canonical link is to indicate to search engines where the authoritative or original URI of the document is. It does nothing beyond that. So the full extent of any additional page size is the number of characters added to the HTML document. That is <link rel=canonical ...>

It is an informational URI only and nothing else and it does nothing else.

  • This doesn't address how a canonical could change the document size. May 17, 2018 at 9:25
  • 1
    "So the full extent of any additional page size is the number of characters added to the HTML document." @StephenOstermiller
    – Rob
    May 17, 2018 at 12:14
  • got it, sorry I missed it May 17, 2018 at 15:15

Your question got me thinking.

A such, I went over to GTMetrix and generated a Performance Report for the duplicate and canonical URL of a website I am currently working on. There was negligible difference in this case. The file size was larger by as little as 2kb, with page load speed varying between 0.2 - 0.6 seconds in difference.

If you ever want to asses any performance based implications, regarding your website, there are a multitude of free online tools. To name a few:

As with any form of Analysis/Reporting, always try to get results from more than one source; as to help with cross referencing.

Best of luck with your ventures!

  • I'm not sure why somebody downvoted this, possibly because of the tool recommendations? In any case, this has the correct answer: "negligible difference." May 17, 2018 at 0:19
  • Me neither. Are there any issues, in sharing relevant and useful resources? Maybe someone has interpreted my answer as an opinion; to which they disagree with.
    – Craig
    May 17, 2018 at 1:13
  • I did because the answer is to generate more work than necessary making it needlessly complicated. I've given the answer, similar to @SimonHayter's comment, and nothing in this answer is worth the time to read it. Any competent web developer knows the answer to this question, no tools needed.
    – Rob
    May 17, 2018 at 2:45

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