Digital Lexicon Hub

A Core Web Vitals metric that measures how quickly a page visually responds to clicks, taps and key presses throughout a visit.

Slow responses to taps and clicks make forms, filters and checkout buttons feel broken, so INP highlights friction that directly affects lead submissions and purchases, especially on mid-range mobile devices.

An ecommerce filter panel shows an INP of 480 ms. Profiling finds a 300 ms JavaScript task on each click; the team splits it into smaller tasks, defers analytics calls and updates the UI first, bringing INP to 170 ms.

INP only covers discrete interactions; scrolling, hovering and zooming are excluded. It needs real-user data, so pages with little traffic may lack field values, and lab tools can only approximate it with metrics such as Total Blocking Time.

Each interaction's latency runs from the input event through event handler processing until the browser presents the next frame. INP usually reports the slowest interaction of the visit, but ignores one of the highest values for every 50 interactions to limit outliers. Thresholds are 200 ms or less for good and above 500 ms for poor at the 75th percentile. INP replaced First Input Delay as a Core Web Vitals metric on March 12, 2024.