The verdict in three sentences
A successful migration or replatforming preserves organic traffic through exhaustive URL mapping and clean 301 redirects. Without that work, the typical loss ranges from -20 to -40 % of traffic for several months. The 2026 SEO support budget sits between 2,500 and 8,000 EUR, an investment far below the cost of a drop in leads.
The pre- and post-migration checklist
A redesign's SEO is won before go-live. Every URL, tag and redirect must be planned and tested.
| Step | Before migration | After migration |
|---|---|---|
| URL mapping | Full export of old site | Verify each redirect |
| 301 redirects | Old-to-new mapping | Bulk test (crawl) |
| Meta tags | Back up title/description | Check they carried over |
| Content | Inventory of traffic pages | Verify presence & indexing |
| Sitemap & robots | Prepare new sitemap | Submit to Search Console |
| Structured data | List existing JSON-LD | Validate error-free |
| Monitoring | Traffic & rankings baseline | Daily monitoring for 8 weeks |
The classic trap: forgetting secondary URLs (PDFs, deep pages) that capture long-tail traffic. A full crawl with a tool like Screaming Frog is essential.
Budget, timeline and quantified risks
Traffic recovery is never instant: Google recrawls and re-evaluates the new URLs gradually.
| Line item | 2026 estimate |
|---|---|
| Pre-migration audit | 800 - 2,000 EUR |
| Mapping & redirects | 1,000 - 3,000 EUR |
| QA & 8-week monitoring | 700 - 3,000 EUR |
| Traffic recovery time | 4 - 12 weeks |
| Loss if done poorly | -20 to -40 % traffic |
| Loss if done well | 0 to -5 % (temporary) |
Full support at 2,500-8,000 EUR stays highly profitable: for a B2B site generating 40 leads/month at a 3,000 EUR deal size, a 30 % drop means 12 lost leads, a shortfall far above the support cost.
Mini case study
Sarah, marketing lead of a mid-sized industrial firm in Amsterdam, replatforms a 480-URL site to a new CMS. She budgets 4,200 EUR of SEO support: audit, mapping of 480 301 redirects, QA and Search Console monitoring over 8 weeks. Result: a temporary -6 % dip in week one, back to baseline in 5 weeks. Without support, a 30 % drop on her 3,200 monthly visits would have cost around 10 monthly leads at 3,000 EUR, far above the 4,200 EUR invested.
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FAQ
How much traffic can I lose in a migration?
With a rigorous plan, loss is limited to a temporary 0-5 %. Without mapping or 301 redirects, it commonly reaches 20 to 40 % and can last several months.
Should I keep the same URLs?
Ideally yes: keeping the URL structure avoids redirects. If the tree changes, each old URL must 301-redirect to its closest equivalent.
How long to recover traffic?
Count 4 to 12 weeks depending on site size and domain authority. Daily Search Console monitoring catches 404 errors quickly.
Are 301 redirects enough?
They are necessary but not sufficient: you must also preserve title tags, traffic content and structured data, and resubmit the sitemap.
When should I schedule go-live?
Avoid commercial peak periods. Switch early in the week so you have several business days of active monitoring.
Let's scope your project. Tell us your URL count, target CMS and switch date, and we will price SEO support (2,500-8,000 EUR) to protect your traffic. 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.
