Technical SEO
Core Web Vitals
Core Web Vitals are three field measurements of user experience: Largest Contentful Paint for loading, Cumulative Layout Shift for visual stability, and Interaction to Next Paint for responsiveness.
What is core web vitals?
Core Web Vitals are three field measurements of user experience: Largest Contentful Paint for loading, Cumulative Layout Shift for visual stability, and Interaction to Next Paint for responsiveness. They are assessed at the 75th percentile of real user visits.
What turns on it
They are the measurable part of the page experience signals and, more practically, they correlate with conversion on most sites.
How it gets implemented
Reported on a rolling twenty-eight day window from real user data, which means a genuine fix takes about four weeks to be fully reflected in the reported figures.
The common misunderstanding
A lab score is not the measurement. A lab test runs once on a simulated device without consent banners, third-party scripts or a cold cache, and it routinely disagrees with field data.
Worth knowing because it comes up in almost every conversation about this.
Where this comes up in the work
It is part of Technical SEO, and more specifically of Indexation control. Across the rest of the work it shows up in:
- Google Ads Management, where it sets the ceiling on finding the geography that converts at half the cost and is capped
- Paid Social and Meta Ads, because making enough creative that fatigue is a schedule rather than a surprise depends on it
- Conversion Rate Optimization, in which it shows up as showing the delivery date before the checkout asks for a card
- Website Design and Development, where it decides carrying out the replatform without losing what the old site earned
What to check
Two questions that establish whether this is actually in order on a given site:
- Whether a new page inherits it automatically or has to be remembered
- Whether the staging behaviour matches production behaviour
Common questions
How do you prove core web vitals is worth fixing?
By measuring it rather than by argument. Reported on a rolling twenty-eight day window from real user data, which means a genuine fix takes about four weeks to be fully reflected in the reported figures.
Is core web vitals just another name for something?
A lab score is not the measurement. A lab test runs once on a simulated device without consent banners, third-party scripts or a cold cache, and it routinely disagrees with field data. Worth clarifying before agreeing to work on it.
Is core web vitals a ranking factor?
They are the measurable part of the page experience signals and, more practically, they correlate with conversion on most sites. The honest framing is that it removes a constraint rather than adding a boost.
What tells you whether core web vitals is in order?
Reported on a rolling twenty-eight day window from real user data, which means a genuine fix takes about four weeks to be fully reflected in the reported figures. The check is cheap; the fix is where the work sits.
Who should be responsible for core web vitals?
Usually whoever owns Conversion Rate Optimization, because finding the form field that costs more completions than it collects answers depends on it. In practice it falls between teams often enough that naming an owner is half the fix. Most briefs that mention this also end up touching Subfolder localisation or Country-code domain, and sometimes WordPress or Shopify.
What does fixing core web vitals involve?
The diagnosis is cheap. The fix ranges from an afternoon to a project depending on how deep it sits in the build, and we scope the second after doing the first. The evidence is in Do we need a blog?. The argument about what it means is in Does Google penalise AI-written content?.
Get a straight answer before you commit
One call, no sequence of follow-up emails afterwards. If the timing is wrong we will leave you to it.