The verdict in three sentences
A site redesign without an SEO plan loses 20 to 40 % of organic traffic in the weeks after launch. A structured migration plan costs 2,000 to 6,000 EUR and pays for itself in a single season of preserved traffic. The two pillars: an exhaustive 301 redirect map and 60-day post-migration monitoring.
Price and scope of a migration plan in 2026
Price depends on the number of URLs, the complexity of the source CMS and the structural change. A domain or technology migration (WordPress to headless) costs more than a simple redesign with stable URLs.
| Migration type | Price (EUR) | Number of URLs |
|---|---|---|
| Redesign with stable URLs | 2,000 - 3,000 | < 200 |
| Rebuild with new architecture | 3,000 - 4,500 | 200 - 1,000 |
| Domain or CMS change | 4,000 - 6,000 | 500 - 3,000 |
| E-commerce migration (catalog) | 5,000 - 6,000+ | 1,000+ |
| Post-migration monitoring (60 days) | included | daily monitoring |
Migration checklist and losses avoided
Every skipped step costs positions. Here are the critical steps and the typical traffic loss they prevent when correctly executed.
| Step | Action | Loss avoided |
|---|---|---|
| Pre-migration crawl | Map all indexed URLs | baseline |
| 301 redirect mapping | 1 old URL = 1 relevant new one | 15 - 25 % of traffic |
| Tag preservation | Title, meta, Hn, canonical, hreflang | 5 - 10 % of traffic |
| Content preservation | Carry over content that performs | 5 - 15 % of traffic |
| Sitemap + Search Console | New sitemap, indexing request | faster re-crawl |
| 60-day monitoring | Fix 404s, redirect errors | 5 - 10 % of traffic |
These percentages are 2026 orders of magnitude from field experience; real risk depends on execution quality.
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Mini case study
Sophie, digital lead at a B2B software vendor in Nantes, rebuilds a 640-page site generating 45,000 organic visits/month. Without a plan, a 30 % loss would mean 13,500 visits/month lost, which on a 2 % conversion funnel and a 4,000 EUR average deal threatens tens of thousands of euros in pipeline. She invests 4,200 EUR in a full migration plan with 60-day monitoring. Result: the loss is contained to 4 % in week one, fully recovered by day 40. The traffic insurance cost less than 10 % of what an uncontrolled drop would have cost her in pipeline.
FAQ
Why do you lose traffic during a redesign? Because old indexed URLs disappear without redirects, optimized tags are not carried over, and the new structure disorients crawlers. Each omission breaks a ranking signal accumulated over years.
Are 301 redirects enough? They are essential but insufficient alone. You must also preserve performing content, tags, structured data and monitor 404s for at least 60 days.
How long to recover rankings? With a good plan, fluctuation lasts 2 to 6 weeks. Without a plan, recovery takes 3 to 6 months, if it happens, because competitors capture the abandoned positions.
Should I migrate all at once or in batches? For large sites (> 2,000 URLs), a batched migration reduces risk. For a brochure site, a well-prepared single switch stays simpler and faster.
When should I schedule the launch? Never on a Friday or before a commercial peak. Choose a low-traffic window so you have the weekend to monitor and quickly fix detected anomalies.
Let's scope your project. Tell us the URL volume, the current CMS and the planned redesign date: we quote an SEO migration plan with 301 mapping and 60-day monitoring. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
