Short answer: rankings drop after a redesign mainly because web addresses change without redirects, or because content that ranked gets cut. To avoid it, list every current URL, map each one to its new address with a permanent (301) redirect, keep the content and titles that bring visitors, and watch Search Console closely in the weeks after launch.

No one can promise that rankings won’t move at all. Google’s own guidance on site moves says to expect temporary fluctuation when URLs change, and that for a small to medium-sized site it typically takes a few weeks for most pages to move. What you can control is whether the move is clean, so that the fluctuation settles instead of turning into a lasting loss. This is the checklist we work through.

Before the redesign: know what you have

You can’t protect what you haven’t listed. Before anything is designed:

List every URL on the current site. Use the sitemap (usually /sitemap.xml), a crawl of the site, your CMS’s page and post lists, and the URLs your analytics shows visits to. Google’s guidance names the same sources: sitemaps, server logs, analytics and the CMS.
Export your best pages from Search Console. In the Performance report, sort pages by clicks and impressions over the last 12 months. These are the pages that bring visitors from Google, and the ones you can least afford to lose. No Search Console yet? Set it up now; our search and analytics setup page explains what it involves.
Note what each important page ranks for. The queries tab for each top page shows the searches it appears for. That tells you which words the new page must still answer.
Save the titles and descriptions of those pages, and any structured data they carry.
Record the email setup. Email runs on your domain’s DNS records, not on the website, but changing hosts is where it most often breaks. See how to move a website without losing email.

The redirect map

This is the single most important document in a redesign. It’s a two-column list: every old URL on the left, its new URL on the right.

Same content, new address: redirect to the new page with a 301 (permanent) redirect. Google recommends permanent, server-side redirects (301 or 308) where possible.
Two old pages merged into one: redirect both to the merged page.
A page you’re dropping: redirect it to the closest relevant page that stays, not to the homepage. Sending everything to the homepage is treated much like a missing page.
Same address on the new site: no redirect needed, but check the page really exists at that address.

Keep the redirects in place for as long as possible. Google’s guidance says at least a year, and that from a visitor’s point of view they could stay indefinitely, because old links in emails, directories and bookmarks keep working.

Carry over the content that ranks

A redesign is a good moment to tidy up, but cutting content is the second big cause of lost traffic.

Keep the pages that bring visitors, even if you rewrite or restructure them. A shorter, prettier page that no longer answers the question can drop out of results.
Keep the topic and the words people search for in the page title, the main heading and the first paragraphs.
Carry over titles and meta descriptions for the important pages, or improve them deliberately rather than by accident.
Keep internal links between related pages, and update them to point straight at the new addresses rather than through redirects.
Keep structured data such as your business details, FAQs or products, if the old site had it.

Build on a hidden staging site, then unhide it

The new site should be built and reviewed somewhere Google can’t index it, such as a password-protected preview. The classic mistake is what happens at launch: the “don’t index this” setting from the staging site is copied to the live site. Two things to check on launch day:

no noindex tag in the pages’ HTML or headers, unless a page really should be hidden;
the live robots.txt doesn’t block the whole site.

On WordPress, also check that “Discourage search engines from indexing this site” under Settings → Reading is off.

Launch-day checklist

Every URL in the redirect map tested: old address → right new page, one hop, status 301.
No noindex on pages that should be found; robots.txt allows crawling.
Canonical tags point at the new addresses, on the live domain.
A new XML sitemap listing only new, live URLs, submitted in Google Search Console and Bing Webmaster Tools.
Contact forms send, phone and email links work, and email on the domain still arrives.
HTTPS works everywhere, and the http:// and www variants redirect to one version.
Analytics is running on the new site.
The site loads quickly on a phone. The free website check gives a plain-language reading in about 30 seconds.

The first weeks after launch

Check Search Console regularly for crawl errors and pages reported as not found. Each “not found” for an old URL is a redirect that’s missing.
Watch indexing move over. Google says the number of indexed old URLs should fall while the new ones rise. If new pages aren’t being indexed, use URL Inspection on a few of them to see why.
Compare clicks and impressions for your top pages against the export you made before launch. A dip is normal at first; a page that falls away and stays down needs a look.
Expect sitemap warnings about redirects if you leave the old sitemap in place for a while. Google says these are normal and can be ignored; remove the old sitemap once the new one is being read.

If you’re stuck on why pages don’t appear at all, our guide to why a website isn’t showing on Google goes through the usual causes.

The full checklist

Before

Every current URL listed
Top pages and their queries exported from Search Console
Titles, descriptions and structured data of key pages saved
DNS and email records copied

Redirect map

Every old URL has a new home or a deliberate decision
Dropped pages point to the closest relevant page, not the homepage
Redirects are permanent (301/308) and server-side

Content

Pages that bring visitors kept, with their topic and key words
Internal links updated to new addresses

Launch

No leftover noindex or blocking robots.txt
New sitemap submitted to Google and Bing
Forms, email and analytics tested

After

Search Console checked for errors in the weeks after launch
Top pages compared against the pre-launch export

How we handle it at B63

When we redesign a website, the redirect map and the content carry-over are part of the job, not an extra: we list the old addresses, redirect each one, keep what brings visitors, build on a private preview and check Search Console after launch. A redesign costs the same as a new site; how much a website redesign costs puts our prices next to typical market quotes.

FAQ

Will a redesign hurt my SEO?

It can, if addresses change without redirects or content that ranked is removed. Done carefully, most of the risk is temporary: Google says some fluctuation is normal during a move and settles over time.

How long do I need to keep 301 redirects?

Google’s guidance says at least a year, and longer if you can. There’s little reason to ever remove them.

Can I change my domain at the same time?

You can, but it adds risk, because every URL changes at once. If you also want a new domain, Google’s site move guidance and the Change of Address tool in Search Console apply. Many businesses are better off redesigning on the same domain first.

How to redesign a website without losing your Google rankings