SEO · Site speed
What Google measures, the scores you need to pass, why INP trips up so many sites, and a fix list you can hand to your developer.
INP must be 200 ms or less
Field data beats lab scores
Extra scripts are the usual culprit
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Core Web Vitals are three measurements Google uses to judge how a page feels to real visitors: Largest Contentful Paint (LCP) for loading, Interaction to Next Paint (INP) for responsiveness, and Cumulative Layout Shift (CLS) for visual stability. To pass, a page needs LCP of 2.5 seconds or less, INP of 200 milliseconds or less, and CLS of 0.1 or less, measured at the 75th percentile of real visits on mobile and desktop.
INP is the newest and the one most sites now fail. It replaced First Input Delay on March 12, 2024, and it measures how quickly your page reacts every time someone taps, clicks or types, not just the first time. This guide explains all three in plain English, with the focus on INP and what to ask your developer.
Time until the biggest thing on screen (usually a hero image or headline) appears. Good: 2.5 seconds or less. Poor: over 4 seconds.
Time from a tap, click or key press until the screen visibly updates. Good: 200 ms or less. Poor: over 500 ms.
How much content jumps around while the page loads. Good: 0.1 or less. Poor: over 0.25.
Google’s guidance is to measure at the 75th percentile. In plain terms, three out of four visits need to hit the “good” mark. A fast office computer on fiber does not count for much; what matters is the typical phone on a typical connection.
Picture a customer on your site tapping “Add to cart,” opening a menu, or choosing a date in a booking form. INP measures the delay between that tap and the moment the screen changes. If nothing happens for half a second, people tap again, give up, or assume the site is broken.
Google breaks each interaction into three parts:
INP looks at interactions across the whole visit and reports one of the slowest, so a single sluggish menu or form can drag the score down. Scrolling and hovering are not counted.
First Input Delay only measured the waiting time before the first interaction was handled. Most sites passed it easily, even when they felt slow. INP measures the full delay for every interaction, so it is a better match for what visitors actually experience, and many sites that passed the old test now fail the new one.
Notice that most of these are business decisions as much as technical ones. Every tool someone added “just to try” has a cost in responsiveness.
You rarely see INP problems on a desktop in the office. They show up on mid-range phones, where the processor is slower and every script takes longer. Typical examples:
A quick test: open your site on an older phone, not on Wi-Fi, and try the three actions that matter most to your business. If any of them feels slow, it probably is.
On WordPress, the usual suspects are heavy page builders, many plugins loading scripts on every page, and sliders. On Shopify, apps are the most common cause, because each one can add its own code to the storefront; removing an app does not always remove its code, so check the theme afterward.
One trap: Lighthouse, the lab test inside PageSpeed Insights, cannot measure INP because no one is tapping the page. It shows Total Blocking Time as a stand-in. A good lab score does not guarantee a good INP for real visitors, so always check the field data.
Yes, but they are not the most important factor. Google says its ranking systems use Core Web Vitals and recommends achieving good scores, but also says it “always seeks to show the most relevant content, even if the page experience is sub-par.” Page experience matters most as a tiebreaker when several pages are equally relevant.
The stronger reason to care is customers. A page that loads slowly, jumps around, or ignores taps loses calls, form fills and sales, regardless of rankings. Google itself advises against chasing perfect scores purely for SEO; aim for “good” and then spend your effort on content and offers.
Want a second opinion on your site’s speed? Book a free 30-minute call. We’ll look at your scores and tell you what we’d fix first, no obligation.
We build custom WordPress sites with performance in mind from the start, and our hosting and support includes constant automated monitoring and malware cleanup. When we take over an existing site, we look at Core Web Vitals alongside rankings and leads as part of our SEO work, and we fix what moves the numbers that matter to your business. See examples on our before and after page.
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200 milliseconds or less at the 75th percentile of real visits. Between 200 and 500 ms needs improvement, and over 500 ms is poor.
Interaction to Next Paint replaced First Input Delay as a Core Web Vital on March 12, 2024.
INP comes from real visitors. If your site lacks enough Chrome traffic, there is no field data. The lab test cannot measure INP and shows Total Blocking Time instead.
Google’s ranking systems use them, but relevance comes first. They matter most when several pages are equally relevant, and they affect conversions either way.
Field data covers a rolling 28-day window, so expect around four weeks before improvements fully show.
