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Core Web Vitals, explained without the jargon

Three numbers decide whether Google thinks your site feels fast. Here is what they measure and how to fix them.

Published 22 July 2026 6 min read

The three numbers

Largest Contentful Paint measures how long the main thing on screen takes to appear — aim for under 2.5 seconds. Interaction to Next Paint measures how quickly the page responds when someone taps — aim for under 200 milliseconds. Cumulative Layout Shift measures how much the page jumps about while loading — aim for under 0.1.

The fixes that actually move them

In our experience most small business sites are fixed by the same short list, applied properly rather than partially.

  • Serve modern image formats at the size they are displayed, and give every image explicit width and height.
  • Render the page on the server so the first view does not wait on JavaScript.
  • Load fonts with a fallback that does not shift the layout when the real font arrives.
  • Defer anything below the fold — chat widgets, maps, video embeds and tracking scripts especially.
  • Delete the third-party scripts nobody looks at. This is usually the biggest single win.

Measure on a real phone, on real data

Lab scores on a desktop connection flatter every website. Test on a mid-range Android over mobile data, and keep an eye on field data over time rather than chasing a single Lighthouse number.

Next step

We build, rebuild and look after websites for businesses across the UK.