The verdict in three sentences
If your site is under 4 years old, scores Lighthouse > 50, and carries technical debt under 30%, a partial redesign at 5,000-9,000 EUR is enough. Beyond that, a full redesign (12,000-22,000 EUR) or a brand-new headless site (20,000-35,000 EUR) becomes worthwhile. The right criterion is not the build price, but the 3-year total cost of ownership.
Quantified decision matrix
Four objective criteria settle the question in 2026.
| Criterion | Partial redesign | Full redesign | New headless site |
|---|---|---|---|
| Site age | < 4 yrs | 4-6 yrs | > 6 yrs |
| Lighthouse score | > 50 | 30-50 | < 30 |
| Conversion rate | > 1% | 0.5-1% | < 0.5% |
| Technical debt | < 30% | 30-60% | > 60% |
| Price EUR | 5,000 - 9,000 | 12,000 - 22,000 | 20,000 - 35,000 |
| Timeline | 3-5 wks | 6-9 wks | 8-12 wks |
If three of four criteria point to the same column, the decision is made. Obsolete or abandoned WordPress plugins weigh heavily: they inflate technical debt and security holes.
3-year total cost of ownership
The real trade-off is TCO, not the initial quote. Here is a 2026 simulation.
| Item (3 years) | Partial redesign | Full redesign | New headless |
|---|---|---|---|
| Initial build | 7,000 | 17,000 | 27,000 |
| Maintenance | 5,400 | 6,400 | 5,800 |
| Hosting | 1,800 | 1,800 | 2,200 |
| 3-year total EUR | 14,200 | 25,200 | 35,000 |
A new headless site costs more upfront but often cuts maintenance thanks to a clean base, narrowing the TCO gap over time.
Mini case study
Thomas, CEO of a Dublin digital-services SME, is torn over his 5-year-old WordPress. Diagnosis: Lighthouse 42, conversion 0.7%, 9 plugins including 3 abandoned, estimated technical debt 45%. Three of four criteria point to a full redesign. He invests 18,000 EUR. Conversion rises to 1.5% on 4,000 visitors/month: 60 leads versus 28. At 25% closing and a 6,000 EUR deal, the extra 32 leads generate about 48,000 EUR of additional annual revenue. The 25,200 EUR 3-year TCO is absorbed within the first half-year after go-live.
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FAQ
When is a partial redesign enough?
When the site is under 4 years old, Lighthouse above 50, conversion above 1%, and technical debt under 30%. In that case 5,000-9,000 EUR covers a design and technical refresh.
At what age should I consider a brand-new site?
Beyond 6 years, with Lighthouse under 30 and obsolete plugins, a new headless site (20,000-35,000 EUR) is often more profitable than patching the old one.
How do I estimate my WordPress technical debt?
Count abandoned plugins, PHP version, console errors, and Lighthouse score. Above 60% debt, a rebuild is generally unavoidable.
Does TCO really change the decision?
Yes: over 3 years, a headless site at 27,000 EUR build can reach 35,000 EUR TCO, while a full redesign at 17,000 EUR reaches 25,200 EUR. That is the real gap to compare, not the quote alone.
Does a redesign lose existing SEO?
Not if a 301 redirect plan and content carry-over are planned. Without them, a badly managed redesign can drop traffic 20-40% for several months.
Let's scope your project. Send us your URL, its age, and your goals, and we will run a diagnosis and price the most profitable partial, full, or brand-new option. 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.
