The verdict in three sentences
For a UK SME whose WordPress site is stuck at 38 on mobile PageSpeed, a migration to headless Next.js costs between £13,000 and £30,000 (excl. VAT) depending on page volume and integrations. The return shows up in three places: speed (LCP from 4.1 s to 1.6 s), maintenance cost (halved) and security (no more 18 plugins to patch). The only real risk, losing Google rankings, is neutralised by a URL-by-URL 301 redirect plan signed off before go-live.
Why a 220-page WordPress site ends up costing so much
Take a typical aerospace subcontractor in the Midlands: 220 pages (products, AS9100 certifications, news, job ads), a premium theme modified by three successive suppliers, and 18 plugins. Every minor update breaks a form or a slider. The site loads 2.8 MB of JavaScript on mobile, and Search Console flags 70% of URLs as "needs improvement".
WordPress itself is not the problem; the stacking is. A headless architecture separates content (the CMS) from presentation (Next.js), so pre-built pages can be served from a CDN.
| Metric | Current WordPress | Headless Next.js (target) |
|---|---|---|
| Mobile PageSpeed | 38 | 85 to 95 |
| Mobile LCP | 4.1 s | 1.6 s |
| JavaScript weight | 2.8 MB | 250 to 400 KB |
| Plugins to maintain | 18 | 0 to 3 |
| Annual maintenance | £5,200 to £7,800 | £2,600 to £3,900 |
| Security incidents / year | 2 to 4 alerts | near zero (static site) |
| Hosting | £35 to £100/month | £0 to £45/month (Vercel, Netlify) |
*2026 order of magnitude observed on B2B sites of 150 to 300 pages.*
What the migration costs, line by line
The budget depends mainly on three factors: the number of page templates, the complexity of forms and integrations (ERP, CRM, careers portal), and whether you keep WordPress as the back office.
| Item | 2026 range (excl. VAT) | Comment |
|---|---|---|
| SEO audit and URL inventory | £1,300 to £2,600 | full crawl, Search Console export |
| Headless CMS selection and setup | £850 to £3,000 | Sanity, Strapi, Payload or headless WordPress |
| Next.js design and build (8 to 15 templates) | £6,000 to £13,800 | reusable components, multilingual |
| Content migration | £1,700 to £4,300 | import script + manual rework of key pages |
| Forms, CRM, job listings | £1,300 to £3,900 | HubSpot, Pipedrive, ATS |
| 301 redirect plan and SEO QA | £850 to £1,700 | 220 URLs tested one by one |
| Team training | £430 to £850 | half-day for editors |
| Total | £13,000 to £30,000 | 10 to 14 weeks |
On subscriptions, a headless CMS costs £0 to £260 per month: self-hosted Strapi or Payload are free, Sanity starts free then runs about £13 per user, and Contentful targets larger accounts.
Keeping SEO risk under control during the switch
A botched migration can cost 30 to 50% of organic traffic for several months. A well-run migration causes at worst a 5 to 10% dip over 3 to 6 weeks, followed by a gain driven by speed.
Non-negotiable rules: keep traffic-generating URLs where possible, 301-redirect every changed URL to its exact equivalent (never to the homepage), carry over title tags, meta descriptions and structured data, submit the new sitemap on launch day, and monitor 404 errors daily for a month.
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Tom, IT Director of a 140-employee aerospace SME near Bristol, receives three quotes: £12,000, £20,500 and £32,500. He picks the £20,500 offer (12 templates, Sanity, 220 pages migrated, redirects, training).
His three-year calculation: current WordPress maintenance at £6,400 per year, i.e. £19,200. Next.js maintenance estimated at £3,000 per year, i.e. £9,000, plus Sanity at £770 per year, i.e. £2,310. Saving: £7,890 over three years. On the sales side, the site generates 25 qualified quote requests per month; a conservative 12% speed-driven uplift means 3 extra requests a month. At a 10% close rate and an average deal of £15,400, that is roughly £55,400 of additional annual revenue. The project pays back in under six months.
FAQ
Do we have to drop WordPress entirely?
Not necessarily. WordPress can stay as the back office (headless mode) if your team is used to it, cutting training and budget by 10 to 15%. The front-end plugins, however, disappear.
How long does migrating a 220-page site take?
Allow 10 to 14 weeks: 2 weeks of audit and scoping, 6 to 8 weeks of development and migration, 2 to 4 weeks of QA and phased go-live.
Will we lose rankings?
With an exhaustive 301 redirect plan, the dip is usually limited to 5 to 10% over a few weeks. Sites moving from 38 to over 85 on PageSpeed often see 8 to 15% more traffic within six months.
Can our marketing team publish on their own?
Yes. A well-configured headless CMS offers a visual editor, live previews and an approval workflow. Half a day of training is enough in 90% of cases.
Is Next.js suited to a multilingual site?
Yes, multilingual routing is native and hreflang tags are generated automatically. Adding a language costs on average £1,700 to £3,400 excluding translation.
Let's scope your project. Send us your site URL and page count: we will price the migration (scope, indicative budget between £13,000 and £30,000, timeline) with a redirect plan. 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.
