How long should you keep 301 redirects after a migration?

You have migrated the URLs or the domain name of your website and, some time later, during a maintenance phase, you or someone on your team asks this recurring question: "How long do the redirects have to stay in place?". There is no single answer to this question! Rest assured, the SEO "it depends" boils down here to two cases that are easy to identify and to add to your SEO redesign checklist, which we will go through together.

To cover this topic properly, it is important to recall the fundamentals. The point of setting up redirects is not to lose the "SEO" of the pages. The "SEO" we are talking about here is the strength of a page (PageRank) and its credibility. This page authority is very often due to the backlinks it receives, and therefore to the related transfer of PageRank. The role of the redirect is therefore simple: to pass the PageRank received on to the new page.

And here you will say: "Yes, but in a migration we do not only redirect pages that have backlinks!". That is why we are going to identify two cases in terms of how long to keep them:

One of the recommendations in these cases, in addition to redirects, is to ask the publishers of the source sites to update the link. Beyond the wishful thinking of this recommendation (which we nevertheless endorse), it is a task which, depending on the number of links, can prove long, tedious, or even impossible to complete exhaustively.

Redirects linked to URLs that receive links must therefore stay in place indefinitely. If there has been an outright change of domain name, remember to renew that domain name. Otherwise, you will be handing your competitors an expired domain name on which they can build a PBN that will then push their own site instead of yours: this is one of the risks of an SEO migration.

Majestic KPIs of the original site of the migration, more than 3 years later

NB: on a site we manage where the domain name change took place at the end of 2017, 3 years later the internal URLs receiving backlinks are still being crawled once or twice a week (see the log extract below). The home page URL is still crawled several times a day to this day (and these are the only ones).

Extract from the Apache logs of the original site (the URLs with backlinks are still being crawled)

URLs that receive no backlinks will gradually disappear from Google's databases because they are no longer referenced there. It is important here not to understand "referenced" as "ranked in SEO" but as "having no reference anywhere else on the Internet". We could even say they are orphaned.

Having no more references and no more content (because redirected or 404), Google will gradually accept the transition to the new URL.

In this second case, you will therefore be able to remove the redirects once Google has completely stopped crawling the old URLs.

Now that you understand the importance of redirect duration for SEO, it is also crucial to know how to set them up correctly. Find out how to manage WWW redirects effectively to ensure a smooth transition of your site. Images follow their own logic, explained in our article on redirecting images.

The only way to know for certain is to carry out what is called log analysis (which we showed in the previous screenshot). To set it up, you can simply retrieve the logs (Apache or Nginx) from your hosting or, if you are technically able to, put the following configuration in place:

1. Isolate the logs by domain name (old and new) if that applies to you
2. Isolate only the visits of Google's robots, via the User Agent for example.

You will then be able to monitor with certainty whether you can actually remove the related redirects.

At the end of the process, we advise you to follow this tutorial to speed up the processing of your migration.

To make sure all the important aspects of your redirect strategy are covered, do not forget to consult our SEO redesign checklist, an indispensable tool for a successful migration process.