INP (Interaction to Next Paint) is a Core Web Vitals metric that measures how quickly a page responds visibly to user interactions such as clicks, taps, and key presses.
INP observes the latency of interactions throughout the entire time a visitor is on the page and reports a value close to the worst one, measured in milliseconds from the moment of input to the next frame painted on screen. A good INP is 200 ms or less, a value between 200 ms and 500 ms needs improvement, and anything above 500 ms is poor. These thresholds are assessed at the 75th percentile of real user visits.
INP became a stable Core Web Vital in March 2024, replacing First Input Delay. FID only measured the delay before processing began on the first interaction, so a page could pass FID while still feeling sluggish. INP captures the full interaction including event handling and rendering, across every interaction, which reflects responsiveness far more honestly. Long JavaScript tasks that block the main thread are the most common cause of poor INP.
The deep guide below covers diagnosis and field-versus-lab measurement in detail.
Related: INP complete guide, Field vs lab data, LCP
Claude Vincent is a technical SEO consultant focused on crawlability, rendering, and AI-search visibility. He writes the field guides and case studies at SEO ProCheck, with a bias toward the durable, unglamorous work that decides whether search engines and AI answer engines can actually read and cite a site.
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