INP (Interaction to Next Paint)
INP measures the time from a user interaction — a click, tap or key press — to the browser's visible response, and has been one of Google's three official Core Web Vitals since March 2024, when it replaced First Input Delay (FID).
In practice
A good INP value is under 200 milliseconds. Unlike FID, which only measured the delay before processing started, INP captures the responsiveness of the whole interaction. The most common cause of poor INP values is heavy JavaScript execution blocking the browser's main thread. In practice it helps to break long JavaScript tasks into smaller pieces and to remove or defer scripts that are not needed.