The verdict in three sentences
Core Web Vitals have become a ranking factor and a conversion multiplier no digital director can ignore. Bringing a corporate site into the green zone costs EUR 3,000 to 7,000 over 3 to 5 weeks depending on technical debt. The return shows fast: +8 to 15 % conversion rate and better mobile ranking.
The three metrics that matter
Since INP replaced FID in 2024, three metrics sum up loading and interaction experience. Each has an official Google target to hit on 75 % of visits.
| Metric | What it measures | Green target | Typical effort |
|---|---|---|---|
| LCP | Largest element render | < 2.5 s | Images, hosting, CDN |
| INP | Interaction responsiveness | < 200 ms | JavaScript, third parties |
| CLS | Visual stability | < 0.1 | Space reservation, fonts |
| TTFB (indicator) | Server response time | < 800 ms | Cache, server, database |
A typical corporate site arrives with LCP at 4 s, INP at 350 ms and CLS at 0.25. The goal is to bring all three below threshold, on mobile 4G, prioritising high-traffic pages.
What it costs, and what it returns
Optimization breaks into workstreams whose price depends on the stack and accumulated debt. Here are 2026 orders of magnitude for a mid-size corporate site.
| Workstream | Timeline | Indicative price | Main gain |
|---|---|---|---|
| Performance audit + perf budget | 3-5 days | EUR 900 | Costed roadmap |
| Image optimization (WebP/AVIF, lazy) | 3-5 days | EUR 800 | LCP -30 to -50 % |
| JavaScript and third-party reduction | 1-2 weeks | EUR 1,800 | INP -40 to -60 % |
| Caching + CDN | 3-5 days | EUR 700 | TTFB halved |
| CLS stability (fonts, layout) | 2-4 days | EUR 600 | CLS < 0.1 |
| QA + 4-week monitoring | 3 days | EUR 700 | Field validation |
A full project bundling these workstreams therefore lands between EUR 3,000 and 7,000. On a site with 100,000 monthly sessions, a 10 % conversion gain on an initial 2 % rate means 200 extra conversions per month.
Mini case study
Sophie, digital director of a B2B services group in London, runs a corporate site with 80,000 sessions/month and a 1.8 % form conversion rate, i.e. 1,440 leads/month. She invests EUR 5,500 in a full CWV optimization over 4 weeks. The rate climbs to 2.0 % (+11 %), i.e. 160 extra leads per month. At a lead value of EUR 250, that generates EUR 40,000 of additional monthly pipeline: the investment is absorbed within the first week after launch.
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FAQ
How much does a Core Web Vitals optimization cost in 2026?
EUR 3,000 to 7,000 for a mid-size corporate site. Price depends mostly on the volume of third-party JavaScript and the state of the front-end stack.
What targets must be reached?
LCP under 2.5 s, INP under 200 ms, CLS under 0.1, on at least 75 % of mobile visits measured in the field (CrUX).
How long to turn green?
Usually 3 to 5 weeks: audit, technical workstreams, then 4 weeks of monitoring to validate field data, which updates gradually.
What conversion gain should I expect?
On average 8 to 15 % depending on the starting severity. The slowest sites at the outset see the most dramatic gains.
Do CWV really influence SEO?
Yes, they are part of the page-experience signal. With equivalent content, a green site is favoured, especially on mobile and on competitive queries.
Let's scope your project. Send us the URL and your current CrUX scores, and we will cost the priority workstreams. 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.
