Core Web Vitals
Google’s experience metricsCore Web Vitals are Google’s three metrics for page experience: LCP measures loading speed, CLS visual stability and INP responsiveness to user input. They are based on real user measurement data and affect search rankings.
Good to know
The thresholds are clear: LCP under 2.5 seconds, CLS under 0.1 and INP under 200 milliseconds. Google scores mobile and desktop separately, and mobile decides, because most searches happen on phones.
The bigger benefit than rankings comes from conversions: a one-second speed-up measurably cuts bounces and lifts conversions. The usual culprits are oversized images, third-party scripts and content jumping caused by ads or fonts. Measure on a mid-range phone over a mobile network, because that is where your customers actually are.
IN PRACTICE
The three metrics in practice
LCP, loading
How fast the page’s largest content element appears. Fixed with image optimisation, caching and a fast server. Target under 2.5 s.
CLS, stability
Whether content jumps during load. Fixed by reserving fixed space for images and embeds. Target under 0.1.
INP, responsiveness
How fast the page reacts to a click or a keypress. Fixed by lightening JavaScript. Target under 200 ms.
PITFALLS
Two ways to measure wrong
Staring at lab numbers
PageSpeed scores come from a simulation; rankings respond to real user data. Search Console field data is the truth.
Speed is treated as a one-off project
Every new script and image eats the gained edge. Without continuous monitoring the scores drift back to red.
FREQUENTLY ASKED
Frequently asked questions
Where do I see my site’s Core Web Vitals?+
In Search Console’s Page Experience report and PageSpeed Insights. The first shows real user data, the second adds a lab measurement.
How much do the scores affect rankings?+
They are one signal among many: good content with weak scores beats weak content with good scores. In an even contest they decide.
What most commonly hurts the scores?+
Unoptimised images, heavy scripts and elements loading without reserved space. Three fixes cover most problems.
When do fixes show in the reports?+
Google’s user data covers a 28-day window, so improvements appear in reports with about a month’s delay.
Who does the fixes, marketing or a developer?+
Both: marketing owns the metrics and priorities, the developer the implementation. Image optimisation and script pruning often succeed without code.
FOR YOUR BUSINESS
Want results, not just definitions?
We go through your goals and propose channels and a budget in 30 minutes, free of charge.
FOR STUDENTS AND NEWCOMERS
Learn the terms, then come and put them to work
The glossary is free study material. Go deeper in our training, and if you want to work in the field, our growing team is looking for people.
Maintained by the VSCY editorial team · Updated 6 Aug 2026 · Part of the marketing glossary (99 terms)
