The verdict in three sentences
A site migration is the moment you win or lose organic traffic: done well it's neutral to positive; botched, it costs 10-15% of visibility. In 2026, a secure migration costs 6,000-18,000 EUR over 5 to 9 weeks, with a 301 redirect plan, preservation of key URLs and an SEO acceptance test. The most underestimated line item is the 90-day post-launch monitoring.
Why a migration loses traffic
Losses almost never come from the new design, but from technical details: URLs changed without redirects, lost tags, altered structure, an outdated sitemap, or a slow new server. Moving from WordPress to a Next.js stack brings speed, but demands total rigor on URL mapping.
| Cause of loss | Frequency | Traffic impact | Prevention |
|---|---|---|---|
| Missing 301 redirects | very common | -8 to -15% | Exhaustive URL mapping |
| Lost title/meta tags | common | -3 to -7% | Controlled export + reimport |
| Content truncated on rewrite | medium | -5 to -10% | Content parity test |
| Bad sitemap/robots config | common | -4 to -8% | Search Console validation |
| Server speed loss | medium | -2 to -6% | Load test before switch |
How much a secure migration costs in 2026
Budget varies with the number of URLs, the complexity of the old site and the level of testing. 2026 orders of magnitude.
| Line item | Range EUR | Delay |
|---|---|---|
| Pre-migration audit + URL mapping | 1,500 - 3,500 | 1-2 weeks |
| New site development (Next.js) | 4,000 - 10,000 | 3-5 weeks |
| 301 redirect plan (up to 2,000 URLs) | 800 - 2,500 | 1 week |
| SEO acceptance + Search Console validation | 1,000 - 2,500 | 1 week |
| 90-day post-migration monitoring | 900 - 2,400 | 3 months |
| Typical project total | 6,000 - 18,000 | 5-9 weeks |
Mini case study
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Sophie, marketing director of an industrial SMB in Montreal, migrates 1,400 URLs from WordPress to Next.js. She budgets 11,000 EUR, including 1,900 EUR for the redirect plan and 1,800 EUR for monitoring. Her 32,000 monthly visits generate 190 leads at an average margin of 850 EUR. A botched migration would have lost her 12% of traffic, i.e. 23 leads/month x 850 EUR = 19,550 EUR of monthly margin. The security premium (about 3,700 EUR over a low-cost migration) pays back in under six days of preserved traffic.
FAQ
Can we keep exactly the same URLs? Yes, and it's recommended when possible: keeping URLs removes the main loss risk. Otherwise, each old URL gets a 301 redirect to its closest equivalent.
How long does Google take to digest the migration? Expect 2 to 8 weeks for a full recrawl and reindexing. Traffic fluctuates in that window: that's normal, hence 90-day monitoring.
Migrate all at once or in batches? For a site under 2,000 URLs, a well-prepared single switch is safer. Beyond that, a batched migration cuts risk but extends the timeline.
What to watch right after the switch? 404 errors, index coverage in Search Console, redirect chains and TTFB. A 404 spike is fixed in hours if caught early.
Can a migration improve SEO? Yes: moving to a fast stack like Next.js often improves Core Web Vitals, which can win traffic after stabilization.
Let's scope your project. Tell us your current CMS, your URL count and your target stack, and we'll cost the migration with a redirect plan and SEO acceptance test. 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.
