How to measure LCP and INP in Safari 26.2 (and what still only Chrome reports)

For years, agency Core Web Vitals programmes had a quiet Safari blind spot. Chrome users filled CrUX, Search Console, and PageSpeed Insights field panels. Safari users on iPhone and Mac still felt slow pages, yet JavaScript often never saw largest-contentful-paint or Event Timing entries in WebKit.

Safari 26.2 (12 December 2025) adds the Largest Contentful Paint API and the Event Timing API in WebKit. You can collect LCP and INP from real Safari sessions through PerformanceObserver, web-vitals, or your RUM vendor. Metric definitions did not change. What changed is whether Safari emits the entries at all.

What still stays Chrome-only in Google's public field tools:

• CrUX remains a Chrome-user sample

• Search Console's Core Web Vitals report still draws on that CrUX world

• PageSpeed Insights field blocks stay Chrome-skewed even after you instrument Safari RUM

• Scheduled Lighthouse / PSI lab runs stay useful for deploy regression, not as Safari field percentiles

Agency checklist we use once Safari 26.2+ volume appears:

• Confirm Safari version share for priority clients before rewriting SLAs

• Upgrade or verify RUM so onLCP / onINP actually receive Safari sessions

• Baseline by browser family for two to four weeks

• Keep CrUX and Search Console as the Chrome field story for SEO conversations

• Re-check Safari INP outliers on a physical device before escalating spikes

Apogee Watcher stays on the portfolio and deploy side: scheduled PageSpeed tests, budgets, and alerts across listed URLs. Safari field collection belongs in your RUM or first-party web-vitals pipeline. Layer the two. Do not pretend a lab score is a Safari percentile.

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