We measured Interaction to Next Paint across 18 million websites. On desktop it is all but solved, with 97.9% passing. On mobile just 82.5% do, the widest device gap of any Core Web Vital.
Source: PageSpeed Matters analysis of Chrome UX Report field data, May 2026.
Responsiveness is nearly universal on desktop and materially worse on phones, a 15.4 point split.
Source: PageSpeed Matters analysis, mobile and desktop 75th-percentile field data, May 2026. CLS is mobile-better.
If you want one number that captures the mobile web running on weaker hardware, INP is it.
Source: INP on Mobile vs Desktop: 97.9% of Desktop Sites Pass, Only 82.5% on Mobile - PageSpeed Matters