How long does it really take to migrate a website in SEO?

Why does Google emphasize 301 redirects so much?

The 301 redirect remains the clearest technical signal that a site has moved. It informs bots that the content has permanently changed its address, unlike a 302 which implies a temporary move.

Without a 301, Google treats the old and new URLs as two distinct entities. The result is: content duplication, dilution of PageRank, and the risk that the old site remains indexed for weeks while the new one struggles to emerge.

Several months of transition, what does that really mean?

Google never gives a precise figure, but field observations suggest that 3 to 6 months is a realistic range for an average site. For larger sites (with several tens of thousands of pages), migration can stretch to 9 to 12 months.

During this phase, the old URLs continue to appear in the SERPs, some pages switch quickly, while others remain stuck. The crawl budget is shared between the two domains, slowing the discovery of the new site.

What factors influence the transition speed?

The crawl frequency of the old domain plays a major role. A site crawled daily migrates faster than one crawled every three weeks. The quality of the internal linking on the new site also speeds up page discovery.

The architecture of the new site must facilitate exploration: a clean XML sitemap, consistent internal links, reduced click depth. If Google has to go through 8 clicks to reach a key page, it will take weeks to get indexed.

• 301 redirect required for each modified URL, no one-size-fits-all rule
• Incompressible latency of several months, regardless of the technical budget invested
• Crawl budget shared between old and new domain throughout the transition
• Daily monitoring essential to spot orphaned or poorly redirected pages
• Traffic anticipation: expect a temporary drop of 15-30% depending on the sectors

Is this timeline of several months consistent with real-world observations?

Yes, and it is often underestimated. On large sites, it is not uncommon to see orphaned URLs from the old domain persist in the index 18 months after migration. Google does not instantly remove old entries; it waits for the crawl to confirm the redirect, then for the new content to be evaluated.

The real problem is that Google never communicates about the speed of PageRank transfer. Some pages transition with their authority intact in a few days, while others lose 40% of their visibility for 6 months before stabilizing. [To be verified]: no public data allows for predicting this behavior.

What gray areas does Google not clarify?

Mueller says nothing about cascading redirects (A → B → C), which are common during successive migrations. Officially, Google follows up to 5 hops, but in practice, a chain of 3 redirects already significantly slows down the authority transfer.

Another troubling silence: the impact of old URLs in 404 error after a partial migration. If 20% of the site has no match on the new domain, should one redirect to the homepage, a similar category, or leave it as a 404? Google remains vague, yet this is a critical SEO decision.

In which cases is the 301 rule insufficient?

When the site structure changes radically. For example, shifting from a product-based hierarchy to a business-use hierarchy. The 301 points to a URL, but if the content or search intent differs, Google may consider the new page irrelevant.

The result is that the page loses its ranking even with a proper 301. Semantic context matters just as much as technical redirection. If the content of the target page does not address the same queries as the old one, the PageRank transfer will not prevent a drop in positions.

What should be implemented before, during, and after the migration?

Before: map all URLs of the old site, identify strategic pages (those generating 80% of organic traffic), and prepare a 1:1 redirect matrix. No generic redirect to the homepage for orphaned pages, unless no semantic match exists.

During: monitor the crawl of both domains via the Search Console. If Google continues to crawl the old site heavily after 3 weeks, it means redirects are not being detected properly. Also check the HTTP codes: a 301 that actually returns a 302 or 307 ruins the entire migration.

After: track the evolution of impressions and positions page by page. A global traffic drop often masks partial collapses on long-tail segments. Reinforce internal linking to pages that are slow to recover.

What mistakes silently sabotage a migration?

First mistake: redirecting too late. Some wait until the new site is perfectly finished before switching. In the meantime, Google has crawled the new domain as duplicate content with the old one, creating confusion in the index for months.

Second mistake: forgetting subdomains and URL variants. A migration also concerns www vs non-www, http vs https, tracking parameters, and separate mobile versions. A single non-redirected URL can break the authority transfer of an entire section.

How can you measure that the migration is progressing normally?

The best indicator remains the crawl ratio between the old and new domains. If after 6 weeks, the old site still receives 60% of the Googlebot requests, the migration is lagging. The goal is to drop below 20% in 2-3 months.

Another KPI: the indexed page rate of the new site. If the Search Console shows 10,000 discovered pages but only 4,000 indexed after 2 months, it indicates a structural problem blocking exploration (insufficient crawl budget, residual noindexes, poorly configured canonicals).

• Establish a 1:1 redirect matrix for all strategic URLs
• Test a sample of redirects with a tool like Screaming Frog before switching
• Monitor the crawl daily through Search Console for a minimum of 3 months
• Ensure that old URLs correctly return a 301 code, not 302 or 307
• Follow the evolution of impressions page by page, not just global traffic
• Reinforce internal linking to pages slow to migrate