How Do 301 Redirects Affect SEO?

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By Boris Dzhingarov

Ask SEO experts about redirects, and they’ll tell you just how tricky redirects can be. Redirecting traffic from one endpoint to another may be necessary in some cases, but the impact of redirects to a site’s SEO performance is not always positive.

The only exception to that rule is the 301 redirect. This type of redirect – when used properly and with a bit of extra care – can actually help boost your site’s SEO performance and produce other positive effects. So, how do 301 redirects affect SEO?

A Permanent Redirect

301 redirects are permanent, meaning that the old URL will soon be unusable. You usw 301 redirects in cases like when you are changing from a string-based URL (i.e. to an SEO-friendly one (

Since 301 redirects are permanent, the destination page will take on the role and traits of the original page. This includes the original page’s SEO parameters, PageRank, page authority, and traffic value. Yes, when used correctly, 301 redirects allow you to move SEO traits of one page to another.

301 redirects will also trigger removal of the old URLs from search results. When crawlers identify 301 redirects on your website, it will automatically list redirected pages and re-index the destination URLs as a replacement to the original ones.

Naturally, it takes time for search engines and their crawlers to identify 301 redirects, and it may take a while before the new URLs get indexed. You want to wait until all SEO traits are successfully moved to the new pages before taking additional steps.

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Doing It Properly

All of the advantages of using 301 redirects we discussed earlier can only be enjoyed when the redirects are set up properly. You also want to make sure that the redirects are permanent (301) rather than temporary (302), since the two produce different results entirely.

There are several cases in which 301 redirects can be incredibly handy, the first one being when you need to correct canonical errors in your URLs. When moving from to, for example, 301 redirect is the best way to go.

The same can be said for when you are moving from string-based URLs to SEO-friendly ones, as explained in the previous example. This includes when you want to add additional parameters (i.e. the category of your page) to the URL and you want to maintain the page’s SEO performance.

Other cases are not so common. Let’s say you are moving from a mixture of PHP and HTML files to an all PHP website. You can use 301 redirects with regular expressions to filter traffic coming to HTML pages and redirect visitors to the corresponding PHP pages.

Regular expressions in 301 redirects can be very powerful, since they can also be used to perform tasks such as changing extensions, redirecting without preserving filename, and changing hostnames entirely. With the latter, you also want to make sure the new site contains the same content.

301 for SEO

301 redirects can also be used specifically for SEO purposes, particularly when you are changing the content or structure of a website. When a page has a strong authority, plenty of backlinks, and relevant content, deleting or moving the page without taking precautions is a big hit to your site’s SEO performance. This is something that can be mitigated using 301 redirects.

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First, you want to make sure that 301 redirects are set up every time you make changes to the URL leading to that page, including the page that needs to be deleted. It is much better to redirect traffic to a relevant page that contains similar content rather than to let visitors go to your standard 404 page. Again, this is something you need to do with extra care.

With the 301-redirect set up, everything about the old page will carry over to the new page. It may take time for crawlers to notice the redirect, but the process is still seamless; you don’t have to do anything to get search engines indexing the new URL and migrating SEO traits to the new page. This is a huge advantage that you don’t want to miss.

When you create a new page for new content, search engines will see it as, well, a new page. It will index it from scratch, and then fill the page’s SEO metrics through further analysis. You are basically starting over with backlinks and other SEO resources. A 301 redirect allows you to avoid starting from scratch and taking a hit on SEO performance.

More Things to Know

At this point, it is easy to see why SEO experts find 301 redirects useful. There is a big SEO impact to be gained from using 301 redirects properly. Before you start adding redirects to your site, however, there are a few more things you need to know.

First of all, 301 redirects are not the default behavior; that role is filled by 302 redirects, which are temporary. You have to specifically define your redirects to be permanent to enjoy the benefits we have covered so far.

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301 redirects also put more stress on your server. Traffic coming to old URLs will need to be forwarded to new ones, and that process is something that the server needs to handle. On a standard shared hosting, 301 redirects can reduce your site’s response time considerably.

That means there is a disadvantage to mitigate; don’t forget that search engine crawlers now use UX-related metrics like response time to rank your site. You need to spend some time optimizing the redirect – and the server – to deal with this risk.

Lastly, monitor your 301 redirects to know exactly when to delete them. At some point, crawlers will stop indexing the old URLs and crawl the replacement ones. It usually takes around 4 to 6 months before search engines deindex your old URLs completely.

You can speed things up by submitting an XML sitemap of all redirected URLs to trigger a new site crawl. Doing a site query on Google will also help you check for old URLs that are still being indexed; this is usually a sign of temporary redirects being used instead of permanent ones.

If you do everything properly, you can continue with the final steps: adjusting backlinks to point to the new URLs and deleting the 301 redirects to free up some server resources. We have tips on how to achieve these effectively too, so stay tuned for more!