The short answer
A contractor site should meet the three Core Web Vitals measurements for how a page loads, responds, and holds still, because a visitor on a phone can leave a slow page. First Call includes a Core Web Vitals performance pass in the site build: measure the three numbers, find the causes, and fix the biggest first.
The three measurements
web.dev defines the set: "Core Web Vitals are the subset of Web Vitals that apply to all web pages, should be measured by all site owners". Each one covers a different failure a visitor feels.
- Loading (LCP). Largest Contentful Paint reports "the render time of the largest image, text block, or video visible in the viewport." On a contractor site that is usually the hero photo or the main headline. web.dev says "sites should strive to have Largest Contentful Paint of 2.5 seconds or less."
- Responsiveness (INP). Interaction to Next Paint "assesses a page's overall responsiveness to user interactions." In plain terms, it is the lag between a tap on the call button or form and the page reacting. A good INP is 200 milliseconds or less.
- Visual stability (CLS). Cumulative Layout Shift is "a measure of the largest burst of layout shift scores for every unexpected layout shift." It is the jolt when a button moves just as you tap it. A good CLS is 0.1 or less, per the web.dev layout shift article.
web.dev recommends judging all three at the 75th percentile of page loads, split by mobile and desktop. A page passes when three of every four visits meet the threshold.
What usually goes wrong on contractor sites
Slow loading can come from an oversized hero image, a slow server, or a chain of redirects. web.dev lists causes such as "multiple server redirects" and visitors located far from the server for slow time to first byte, plus a delay while the image itself downloads. Responsiveness problems can come from heavy third-party scripts, such as chat widgets and tracking tags. Layout shift comes from images without set dimensions, late-loading fonts, and embeds like booking forms that push the page down.
Retest after any change to images, scripts, or embeds, since each can reintroduce a problem.
How the pass works
The usual method is field data where a site has enough traffic and lab testing where it does not, so the first numbers say which they are. Then the fixes go in order of size: the image and server work that moves loading, then the scripts that hurt responsiveness, then the layout shifts. Check each change on a phone.
The pass is part of the build described on the contractor website design page, and it respects the call path: the tap-to-call button and the call tracking code are tested together, so the tracking does not slow the very action it measures.
What is measured, and what is not promised
We report the three values and what changed. We do not promise a ranking or call increase from passing them. For the wider plan, see the home service website design overview and the site speed items in the contractor checklist. The free 100-point audit reads the security headers, server response time, and tap-to-call link of your site in seconds.
Questions about Core Web Vitals
What counts as a good Core Web Vitals result?
- A page passes each measurement when three of every four visits, split by mobile and desktop, meet the threshold given above. The three measurements cover loading, responsiveness, and visual stability, and the web.dev articles linked on this page give the definitions.
Will passing Core Web Vitals get my site more calls?
- We cannot promise that. Passing means fewer visitors leave because a page was slow, jumpy, or unresponsive, which removes one reason to lose a call. Whether calls rise depends on the offer, reviews, and traffic too, which is why we track calls separately.