The verdict in three sentences
A WordPress-to-headless migration (Next.js + API CMS) costs 12,000 to 28,000 EUR in 2026 for a B2B site of 200-400 URLs. The critical line item is not design, it is the 301 redirect plan and the SEO acceptance testing that protect your traffic. Done right, the switch takes LCP from 4.2s to 1.8s and delivers +15 to +30% organic traffic within six months.
What you actually pay for
The budget breaks down by work package. A heavy legacy WordPress (stacked themes, 25 plugins, page builder) costs more to migrate than a clean site, because you must audit then clean the content first.
| Item | Range EUR | Timeline | Note |
|---|---|---|---|
| Technical audit + URL mapping | 1,500 - 3,000 | 1 wk | Inventory of 300 URLs, content, SEO |
| Headless architecture (Next.js + CMS) | 4,000 - 9,000 | 3-4 wk | Decoupled front, content API |
| Content + media migration | 2,000 - 5,000 | 2 wk | Articles, WebP images |
| 301 redirect plan | 1,000 - 2,500 | 1 wk | Old > new mapping |
| SEO acceptance + go-live | 1,500 - 4,000 | 1-2 wk | Tests, sitemap, Search Console |
| Editor training | 1,000 - 2,500 | 3 d | CMS onboarding |
| Total | 12,000 - 28,000 | 8-12 wk | By volume and complexity |
The performance gain in numbers
Headless separates rendering from content: pages are pre-generated or served via CDN, without the PHP + database overhead on every visit.
| Metric | WordPress before | Headless after | Effect |
|---|---|---|---|
| LCP (main load) | 4.2s | 1.8s | -57% |
| INP (interactivity) | 480 ms | 140 ms | Below the 200 ms threshold |
| Average page weight | 3.4 MB | 1.1 MB | WebP/AVIF images |
| Mobile Lighthouse score | 42 | 94 | +52 pts |
| Organic traffic at 6 months | base 100 | 115-130 | +15 to +30% |
| Bounce rate | 61% | 44% | -17 pts |
Mini case study
James, digital lead at an industrial components manufacturer in London, runs a 320-URL WordPress site that loads in 4.2s on mobile. He is losing rankings on product pages. Headless migration quote: 19,000 EUR over 10 weeks. His organic traffic is 12,000 visits/month, 3% of which convert into a quote request worth 4,200 EUR average margin. A 20% traffic lift means 2,400 more visits, i.e. 72 extra annual requests. Even at a 12% close rate, that is roughly 8.6 additional contracts per year, well above the migration cost in the first year alone.
FAQ
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How long does a headless migration take?
Expect 8 to 12 weeks for a 300-URL site, including 2 weeks for SEO acceptance testing alone. A simpler site (under 80 pages) can wrap in 5 to 6 weeks.
Will I lose rankings during the switch?
Not if the 301 redirect plan is complete: every old URL points to its new counterpart. Without that mapping, 60% of rebuilds lose traffic; with it, loss is marginal and recovered within 4 to 8 weeks.
Will my editors still be able to edit content?
Yes. The headless CMS (Sanity, Strapi or equivalent) offers a clean editing interface. Plan 3 days of training, about 1,000 to 2,500 EUR.
Is headless justified for a small brochure site?
Under 30 pages with no strong performance stakes, a well-optimized WordPress often suffices. Headless pays off from significant traffic or multi-channel needs (site + app + kiosks).
Can I keep WordPress as the back office?
Yes, in "headless WordPress" mode: WordPress acts as the content API and Next.js handles display. You keep editorial habits while gaining the performance of a decoupled front end.
Let's scope your project. Send us your URL volume, current CMS and performance target: we price the migration, 301 plan and training. 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.
