INP (Interaction to Next Paint)

Interaction to Next Paint is the Core Web Vital that assesses a page's overall responsiveness by observing the latency of qualifying click, tap, and keyboard interactions throughout a visit. An interaction runs from the user's input until the browser presents the next frame, including input delay, event-handler processing, and presentation delay. The reported value is usually the longest observed interaction, with an outlier adjustment on pages that receive many interactions.

Why it matters: For field data, an INP of 200 milliseconds or less is considered good, above 200 and up to 500 milliseconds needs improvement, and above 500 milliseconds is poor. Evaluate the 75th percentile of page visits separately for mobile and desktop rather than treating one fast test as representative. Use real-user monitoring or Chrome UX Report data to find affected pages and interactions, then reproduce them in a lab trace and separate input delay, processing time, and presentation delay. Common work includes reducing or breaking up long main-thread tasks, limiting unnecessary first- and third-party JavaScript, shortening event callbacks, yielding during lengthy work, reducing expensive rendering, and giving prompt visual feedback. INP does not measure hover, scrolling, the completion of later network work, or every asynchronous effect. It replaced First Input Delay as a Core Web Vital in March 2024 because it covers eligible interactions across the visit rather than only the first interaction's input delay.