The verdict in three sentences
Migrating a site without breaking SEO is not about luck but about method and rigorous acceptance testing. For 400 URLs, expect a budget of EUR 6,000 to 12,000 over 6 to 8 weeks, where the critical item is the exhaustive 301 redirect plan. A well-run project targets less than 5% organic traffic loss at 90 days, with a return to normal within 2 to 4 months.
The budget of a controlled migration
Migration has a cost, but every euro covers a specific risk. Losing 30% of traffic on a lead-generating site costs vastly more than the acceptance test. Here is the 2026 breakdown for a 400-URL site.
| Item | 2026 range (EUR) | Objective |
|---|---|---|
| Crawl + URL mapping | 800 | Full inventory, no forgotten URL |
| 301 redirect plan | 600 - 1,500 | 1 old URL = 1 new URL |
| Content migration + tags | 2,000 - 4,000 | Title, meta, Hn, structure |
| Pre-launch SEO acceptance | 1,200 | Validation before go-live |
| 90-day post-migration follow-up | 1,000 - 2,500 | Fixes, rank monitoring |
| Indicative total | 6,000 - 12,000 | < 5% loss at 90 days |
The redirect plan is the centrepiece: every old indexed URL must 301-point to its equivalent, with no redirect chain or loop.
The 6 anti-traffic-drop steps
A migration is run like a project, not a simple deployment. The table below sums up the sequence and typical timelines.
| Step | Duration | Key deliverable |
|---|---|---|
| 1. Crawl current site | 3-5 d | Full list of indexed URLs |
| 2. Old/new mapping | 5-7 d | 301 correspondence table |
| 3. Content + tag migration | 2-3 wk | Migrated content, meta kept |
| 4. Staging SEO acceptance | 1 wk | Validated checklist before prod |
| 5. Go-live + 301 | 1 d | Redirects active, sitemap submitted |
| 6. 90-day follow-up | 90 d | Rank report + fixes |
The classic mistake is neglecting step 4: a staging acceptance test catches forgotten noindex tags, 404s and redirect chains before they cost rankings.
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Mini case study
Thomas, digital lead of an SME in Toronto, migrates a 400-URL site generating 12,000 organic visits per month and 45 leads. Without a redirect plan, a 30% loss would cost 13.5 leads/month; at a value of EUR 220 per lead, that is EUR 2,970/month lost. He invests EUR 9,000 in a framed migration: the real loss is 4% at 90 days, i.e. under 2 leads/month, and traffic exceeds its former level by month 4. The migration pays for itself in under two months versus the uncontrolled scenario.
FAQ
What is the minimum budget for a serious migration? For a 300-500 URL site, budget at least EUR 6,000 in 2026. Below that, the redirect plan and SEO acceptance are usually rushed.
How long to recover traffic? With good execution, the loss is under 5% at 90 days and traffic returns to its initial level, or exceeds it, between month 2 and month 4.
Are 301 redirects enough? They are necessary but not sufficient: you must also keep title/meta tags, the Hn structure, structured data, and submit a new sitemap to Search Console.
Should we migrate all at once or in batches? For 400 URLs, a well-prepared single switch is preferable; beyond 2,000 URLs, a batched migration reduces risk, with a higher follow-up cost (EUR 2,000 to 4,000).
What to watch in the first days? 404s, server errors, redirect chains and the ranking of your top 20 priority keywords: daily monitoring during the first week avoids nasty surprises.
Let's scope your project. Tell us the number of URLs, your target CMS and your current traffic, and we will quote a secured migration. 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.
