Building a 301 redirect plan for a relaunch: mapping old URLs to new ones

A 301 redirect plan is a simple but crucial list: for every old URL, you note which new URL it should redirect to from now on, so that your visitors, links and rankings survive your relaunch. The short answer to how you build such a plan: first map all your existing URLs, connect them one-to-one to the most relevant new page, decide deliberately what you redirect or let expire, and test everything before you go live. In this article we walk through that mapping step by step, so that you don’t discover after launch that half your traffic lands on a 404.

This is the tactical deep dive into one of the steps from our broader playbook for a website migration without ranking loss. There we look at the entire migration project; here we zoom fully in on the redirect mapping itself, because that is the step where most relaunches come unstuck. If you’re looking for the broader framework, read our guide on building a B2B website.

The plan itself breaks down into five steps that you’re best off working through in this order, from taking inventory to monitoring after going live:

What exactly is a 301 redirect plan?

A 301 redirect plan is a structured list that maps every existing URL to its successor on the new site. A 301 is a permanent redirect: it tells browsers and search engines that a page has definitively moved to a new address. The difference with a temporary 302 matters, because only with a 301 does Google know the move is permanent and is allowed to carry over the signals you’ve built up.

That carrying over is precisely why the plan matters. Google confirms that ranking signals such as PageRank and inbound links are passed on cleanly through a 301 redirect. Skip a valuable page and the chain breaks: the visitor gets a 404, the link value evaporates and the position you spent years building is gone. A relaunch should protect your positions, not reset them.

Important to grasp: a redirect plan is not a technical afterthought you improvise on launch day. It’s work you do in advance, while the old site is still fully live and you can therefore take stock of everything there is to lose.

How do you create a complete URL inventory?

You never start with mapping, but with taking inventory: what you don’t map, you also can’t redirect. A reliable inventory comes from multiple sources, because no single source is complete on its own.

• A crawl of your site. A crawler like Screaming Frog or a comparable tool walks through your entire site and gives you every internal URL, including existing redirects and broken links.
• Your XML sitemap. It shows the URLs you yourself mark as important.
• Google Search Console. Here you see which pages are actually indexed and on which URLs people arrive from the search results.
• Your analytics. This tells you which pages bring in traffic and, more importantly, leads.
• Your backlink data. Pages with external links are extra valuable, because you absolutely don’t want to squander their link value.

Merge those lists into a master file and deduplicate it. For each URL, add some context right away: how much traffic it draws, whether it has external links and whether it converts. Those columns will determine your priorities later. A page with hundreds of visitors per month and strong backlinks deserves more attention than a forgotten news item from 2018. This inventory is also, incidentally, the moment to trace existing redirect chains, so that you clean them up in one go.

How do you map old URLs one-to-one to new ones?

The golden rule is simple: map every valuable old URL to the most relevant new page, one to one. Google’s John Mueller put it sharply: a 301 for a disappeared page makes sense if you have a one-to-one replacement, otherwise Google presumably treats the redirect as a soft 404.

That word relevant is the crux. A product page should point to the new product page, a blog article to the replacing article, a service page to the corresponding new service. The mistake you want to avoid is redirecting everything en masse to the homepage because that’s faster. Google sees such catch-all redirects as soft 404s, ignores them and doesn’t pass on the signals of those old pages. You’re then left with a tidy-looking site whose SEO value has quietly leaked away.

Work in your master file with two columns side by side: the old URL and the new target URL. Go through them row by row, starting with the pages that have the most traffic and the most leads. Keep your new URL structure as close to the old one as possible where you can, because the less that changes, the smaller the risk. How to build that new structure logically, you’ll read in our guide on website architecture and SEO. When mapping, also watch out for redirect chains: let A point directly to C instead of via B, because superfluous intermediate steps slow down and weaken the redirect.

What do you do with pages that have no logical new destination?

Not every old URL has a natural successor, and that’s fine as long as you decide about it deliberately. For each page without an obvious match, you have roughly three choices.

The first: if there’s no exact replacement but there is a strongly related topic, map it to the nearest relevant page, for example the overarching category or a related article. The second: if it’s a page with traffic or links but without any relevant destination, consider recreating that content on the new site rather than letting it disappear. The third: if a page has no traffic, no links and no value, let it expire cleanly with a 404 or 410 instead of forcing a contrived redirect.

That last choice feels counterintuitive, but an honest 404 for worthless content is better than an irrelevant redirect that gets treated as a soft 404 anyway. The trade-off you make here belongs to the broader website redesign process, in which you decide anyway which content moves along and which you let go.

How do you test your redirect plan before launch?

You test a redirect plan before going live, not afterwards, because discovering mistakes while your traffic is already draining away is the most expensive way to do it. So first set up your redirects in a protected test or staging environment that’s shielded from search engines, and work through your master file systematically.

Check per line whether the old URL actually returns a 301 and not accidentally a 302, a 404 or a chain of multiple hops. A crawler can test your entire redirect list in one go and immediately flags where things go wrong. Don’t forget the edge cases: URLs with and without a trailing slash, capitals, old parameters and variants with or without www or https. A complete plan catches all those variants.

Schedule the go-live itself at a quiet moment and keep your master file to hand as a checklist. How to protect your positions even further around launch, you’ll read in maintaining rankings after a website redesign.

How do you monitor the redirects after going live?

After launch, monitoring begins, because a redirect plan is only successful if it keeps holding up in production. Keep a close eye on your 404 reports in Search Console: every unexpected 404 on an old URL is a hole in your plan that you close right away. Also check that the traffic to the old URLs gradually shifts to the new pages.

Track as well whether Google picks up your new URLs and lets the old ones drop out of the index. That usually takes several weeks to months, so a temporary fluctuation is normal. A lasting decline on a specific page, on the other hand, is a signal: often a redirect is missing or points to a destination that’s too little relevant. A well-maintained redirect plan is thus not only a launch document, but also your most important diagnostic aid in the weeks that follow.

The short summary

A 301 redirect plan stands or falls on completeness and relevance. Map all your URLs from multiple sources, connect every valuable old URL one-to-one to the most relevant new page, decide deliberately what you let expire, test everything in a protected environment and monitor your 404s after going live. If you do that carefully, it’s not only your content that moves along, but also the rankings and leads you built with it over the years.

Wondering whether your redirect mapping is watertight, or do you simply want to play it safe with your relaunch? We’re a small, experienced B2B team that builds your site while preserving what works, and that tells you honestly where the risks lie. See without obligation how we build conversion-focused websites that protect your traffic and leads.

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Frequently asked questions about a 301 redirect plan

What’s the difference between a 301 and a 302 redirect?

A 301 is a permanent redirect and tells search engines the move is lasting, which makes ranking signals move along. A 302 is temporary and doesn’t pass on that signal. During a relaunch you almost always use 301s, because the old URLs aren’t coming back.

Can I redirect old URLs to my homepage?

Preferably not. Google treats mass redirects to the homepage as soft 404s, ignores them and doesn’t pass on the link value of those pages. Map each page to the most relevant new destination, and let a page without value expire cleanly with a 404 instead.

How long should I keep my 301 redirects in place?

Keep them for at least a year, and preferably permanently for pages with strong external links. As long as people still arrive via old links or bookmarks and search engines know the old URLs, the redirects keep doing their work.

Which tool do I use to test my redirects?

A website crawler like Screaming Frog lets you check your entire redirect list in one go for status code and chains. For individual URLs, inspection in your browser or in Google Search Console is enough to see whether an address returns a correct 301.