Do HTML errors affect search impressions? (The errors shown in red when right-clicking the bottom-right-hand corner of a website.) And can correcting them eventually improve traffic?

I had lots of little HTML errors on my site (all pages) and I fixed them all on the 11th Dec. I've been told that this should increase the search impressions of my pages. Since then the impressions haven't gone up, but maybe it is a matter of time? It's been 2.5 weeks now.

I believe many (though not all) of my pages are otherwise well keyword-targeted.

Thank you!

  • 2
    In short yes and no. It depends on the error. Google prefers HTML 4.2, but as long as you are 4.0 compliant and the errors are nothing tragic and within the scope of error correction that exist within the parser, then you should be fine. In other words, if it still works within your browser there is no harm. Some will argue, but this is right from the horses mouth. It is preferable that code be correct and compliant of course. But mixing standards some and smaller errors have absolutely no effect. BTW- the metrics on this is almost binary. Google does not grade sites and adjust SERP placement.
    – closetnoc
    Dec 27, 2014 at 17:00
  • I just recently changed my doctype to html 5 although I was using bits of html 5 code within the pages. That was one of the errors. What do you mean by "BTW- the metrics on this is almost binary. Google does not grade sites and adjust SERP placement."
    – CHR
    Dec 29, 2014 at 20:55
  • 1
    As far as code goes, Google forgives errors rather easily and does not care if you mix standards, however, if you go out of the standards, then there is one metric- compliant or not compliant. And even then, the effect is rather small.
    – closetnoc
    Dec 29, 2014 at 21:33
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    BTW- My home page has about 60 errors. No worries. It gets more traffic than the entire site. You will find that many of the errors you will see as minor and repetitive. Pay attention to the big ones and do not worry about the piddly stuff. If you can fix them all then do it. Otherwise, it is not important unless it is full broken and cannot be rendered.
    – closetnoc
    Dec 29, 2014 at 21:53
  • 1
    Fixing errors is a good thing to do. There is one Google engineer on this board. And I have had a look at Googles schema and business rules about 2 years ago. It was absolutely complete something any SEO would kill for. Plus I have worked on some niche search engines and was a programmer back in the days of the ARPA-Net (became the Internet) and worked on routing and such. I have been at this for 30 years. But here is the thing. Anyone can be wrong and make mistakes. Just know that much of the SEO experts are mostly guessing around the edges. The rest are parrots. I say follow common sense.
    – closetnoc
    Dec 29, 2014 at 22:26

1 Answer 1


In short, yes.

But, good HTML does not automatically mean you will get more traffic, so the fact that you have not seen an increase may not have anything to do with your HTML.

To your questions about HTML, some ways that bad HTML can affect your search engine indexing and traffic.

Sign-up for Google Webmaster tools, go to Search Appearance, then to HTML Improvements. Notice that there is a section labeled "Non-indexable content". If HTML is so malformed, then search engines might not even be able to index it.

Click on Security Issues. Malformed JavaScript could produce issues here and that could seriously affect your entire site's indexing.

Use Google PageSpeed Insights. Page loading time is part of Google's ranking algorithm, and malformed HTML will slowdown your page rendering.

Even if you do not have advertisements, you can sign up for Google AdSense. AdSense gives you a "Site Health" score. From the explanation of the score:

We’ve analyzed how well your pages with the highest number of ad requests perform on desktop computers. Improving the performance of these pages can lead to an improved experience for your users and increased traffic and earnings.

Jakob Nielsen, a usability expert, says that response times longer than two seconds cause users to leave your site and that response times longer than 10 seconds cause users to assume your site is completely broken. In other words, long response times will increase your bounce rate and reduce your page views per session. Malformed HTML increases page loading times.

Summary: bad HTML (and JavaScript) can hurt your search engine indexing and traffic but good HTML will not necessarily improve your traffic.

  • Thank you for your answer. I find it very useful. Too bad that the question is marked as duplicate so all this information will be deleted soon.... But I will take a screenshot and trust the better judgment of the moderators !
    – CHR
    Dec 29, 2014 at 20:48
  • I had no HTML improvement suggestions in GWT - had dealt with those long time before. No problems with non-indexable content. Also no security issues. Google PageSpeed Insights gives the site a score of 41/100 (in the red) with many suggestions for changes most of which I don't understand (might have to ask new questions for each). Google AdSense site health score is 3/5. Pingdom website speed test reports a grade of 72/100, load time 3.69s (I assume it's average over my pages but could be just the homepage).
    – CHR
    Dec 29, 2014 at 21:11
  • SEO is a massive industry for a reason. Improving your HTML will have minimal impact on your SEO, but learning about SEO could help. Dec 29, 2014 at 22:09

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