The verdict in three sentences
A full Core Web Vitals optimization on a Berlin B2B website costs 2,500 to 8,000 EUR in 2026, depending on technical debt and CMS. The three thresholds to clear are LCP < 2.5 s, INP < 200 ms, CLS < 0.1, measured on field data (CrUX), not in the lab. The return is twofold: +15 to +25 % conversion and a gain of 5 to 12 SEO positions in 4 to 8 weeks.
Cost by technical debt
Price depends mainly on the starting state. A recent Next.js site is fixed quickly; a plugin-heavy WordPress needs real work. Here are the 2026 ranges.
| Site profile | Price | Work | Timeline |
|---|---|---|---|
| Light (Next/Astro) | 2,500 - 4,000 EUR | Images, fonts, JS | 4 weeks |
| Medium (optimized WP) | 4,000 - 6,000 EUR | + cache, critical CSS | 6 weeks |
| Heavy (WP + builders) | 6,000 - 8,000 EUR | + template rebuild | 8 weeks |
| Complex custom | quote | Arch + CDN + edge | 8-10 weeks |
Before / after metrics
A well-run project moves every metric past the green threshold. Here is a representative 2026 result on a B2B catalog site.
| Metric | Before | After | Google threshold |
|---|---|---|---|
| LCP | 4.3 s | 2.1 s | < 2.5 s |
| INP | 340 ms | 160 ms | < 200 ms |
| CLS | 0.24 | 0.05 | < 0.1 |
| Mobile score | 48 | 92 | > 90 |
| Bounce rate | 61 % | 44 % | — |
High-impact levers: AVIF/WebP compression and image sizing, preloading the font and LCP element, JavaScript code-splitting, reserving space to avoid CLS, and edge caching via a CDN. On mobile 4G, every second of LCP saved improves conversion by about 3 to 7 %.
Mini case study
Lukas, marketing director of a components manufacturer in Berlin, invests 5,200 EUR for a medium WP site. Organic traffic: 6,000 visits/month, form conversion 2.1 %, i.e. 126 leads. After optimization, conversion reaches 2.6 % (+24 %) and traffic gains 9 average positions, i.e. +18 % visibility. Combined result: about 190 leads/month versus 126. At a lead value of 45 EUR, the monthly gain is around 2,880 EUR: the investment pays back in under 2 months.
FAQ
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
How much does Core Web Vitals optimization cost in 2026?
Between 2,500 and 8,000 EUR depending on technical debt. A modern site sits at the low end, a heavy WordPress at the high end.
Which thresholds should I target?
LCP < 2.5 s, INP < 200 ms, CLS < 0.1, measured on CrUX field data. A 90+ mobile PageSpeed score confirms the pass.
What is the real impact on sales?
A conversion gain of 15 to 25 % is realistic. Every second of LCP saved on mobile adds 3 to 7 % conversion.
How long does the work take?
Between 4 and 8 weeks depending on the CMS. First CrUX gains stabilize after 28 days of measurement.
Is INP really critical?
Yes, since it replaced FID in 2024. An INP above 200 ms penalizes experience and mobile ranking.
Let's scope your project. Send us your URL and CMS: we measure your Web Vitals and price the work within 48 h. 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.
