Open Search Console. Desktop is green, mobile is red. Google is reading the red column.
Google finished switching Search to the smartphone crawl in October 2023. The crawler that decides what your pages contain, and how they rank, is a smartphone agent.
Your Analytics can show a desktop majority this year. Both can be true. The 1440px mockup is still the wrong source of truth for what Googlebot and a lunch-break searcher see.
A lot of small business sites still treat the phone as a CSS breakpoint. The phone is a slower computer, a worse network, and the place a local searcher decides whether to call you.
Google already grades the phone
Page experience uses three field metrics from real Chrome users, at the 75th percentile, over about 28 days. A lab score in PageSpeed Insights is a rehearsal. Search Console is the show.
Largest Contentful Paint (LCP) is when the biggest thing on screen paints. Good is 2.5 seconds or faster. Poor is over 4.
Interaction to Next Paint (INP) is tap or click until the next paint, across the whole visit. Good is 200 milliseconds or faster. INP replaced First Input Delay on March 12, 2024.
Cumulative Layout Shift (CLS) is unexpected layout jump. Good is 0.1 or under.
Google retired the Mobile Usability report and the Mobile-Friendly Test on December 1, 2023. The replacement is the Mobile Core Web Vitals report. One bad metric on a template can paint a whole URL group Poor.
A Lighthouse 95 with a failing CrUX LCP does not earn the Good page-experience signal. If someone told you the March 2026 core update moved LCP Good to 2.0 seconds and INP to 150 milliseconds, that is not in Google's docs. web.dev still lists 2.5s / 200ms / 0.1.
John Mueller has said it plainly: Core Web Vitals are a ranking factor, more than a tie-breaker, and they do not replace relevance. Poor mobile scores can hold a good page back in a crowded niche. For most SMBs the bigger tax is conversion on the phone, not a ranking cliff.
Half of mobile origins still fail
HTTP Archive's Web Almanac 2025 (CrUX, July 2025 crawl) put mobile origins that pass all three vitals at 48 percent. Desktop sat at 56 percent. Still a coin flip.
LCP is the usual miss for a service business. On mobile, 62 percent of origins hit Good LCP. 13 percent land Poor, almost double desktop's 7 percent Poor rate.
INP Good is 77 percent on phones and 97 percent on desktops. That is a 20-point interactivity gap on the same page.
CLS is the metric most sites already pass. Mobile CLS (81 percent Good) beats desktop (72 percent).
Pages still jump. That is not why most small-business sites fail the full set.
The mid-market sits in the worst band. The 1,000 most-visited origins pass 51 percent of the time. The 100,000 most-visited sit at 37 percent, with the long tail back up at 48 percent.
Tiny brochure sites inherit a simple template. Huge sites pay for performance work. The plumber, the MSP, the shop with ten tracking pixels sit in the trough: complexity with no owner.
Hosted builders that control images and hosting pass all three vitals on roughly 70 to 85 percent of origins. Self-hosted stacks with a page builder and a pile of plugins sit closer to 46 percent.
Taps are usually fine. Loading is what tanks it.
Same page, slower machine
Median lab Total Blocking Time on mobile in 2025 was 1,916 milliseconds, up 58 percent from 2024. Desktop median: 92 milliseconds.
Field INP got better while lab blocking got worse. Phones got faster. Sites got heavier.
Extra JavaScript hides on a laptop on office Wi-Fi. It shows up on a four-year-old Android on LTE.
Images are the LCP element on 76 percent of mobile pages. JPG still accounts for about 57 percent of those. And 16 to 17 percent of mobile pages still mark the LCP image lazy:
<img src="/hero-2400.jpg" loading="lazy" alt="">
That line tells the browser to wait on the biggest thing the phone has to paint. Width and height are often missing too. Almanac 2025 still found at least one unsized image on 62 percent of mobile pages.
Then a cookie bar or a chat bubble shoves the Call button after the tap target has already moved.
The tax hits before sales speaks
Vodafone Italy ran a real A/B. A 31 percent better LCP produced 8 percent more sales, 15 percent better lead-to-visit, and 11 percent better cart-to-visit.
Deloitte and fifty-five, in Milliseconds Make Millions (2020, commissioned by Google), isolated four speed metrics. One tenth of a second faster on mobile: 8.4 percent more retail conversions, 9.2 percent higher average order value, and an 8.3 percent drop in lead-gen bounce.
Desktop still converts about twice as well as mobile on a lot of commerce sites. Phone friction is eating those visits.
Local intent is tighter because the clock is shorter. Google's older Think with Google research (the numbers that still circulate): 76 percent of people who search something nearby on a smartphone visit a business within 24 hours. Twenty-eight percent of local searches result in a purchase.
If the Maps listing already won the pack and your site takes four seconds to paint, with a jumpy Call button, the lead dies after Google sent it. Sales never sees those people. Website speed for a local business is whether that person actually calls.
Dan Taylor looked at 107,000 AI-visible pages in January 2026 (Search Engine Land). Same shape as organic: no real upside past good enough, real downside at severe failure.
Fix Poor. Don't chase a 100.
Secondary pages pass overall mobile Core Web Vitals more often than homepages (56 percent vs 45 percent) because of cache and simpler templates. Mobile INP is now worse on those interior pages (69 percent Good vs 80 percent on homes).
Quote forms, calendars, filters, and late-firing scripts live on the URL that is supposed to convert.
Watch the red column in Search Console, not a desktop Lighthouse screenshot. PageSpeed loosened its lab CPU throttle in December 2024 (4x down to 1.2x), so lab scores jumped while field data did not.
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