What is Interaction to Next Paint (INP)?

Interaction to Next Paint (INP) measures how quickly your page responds when someone taps, clicks or types — the gap between the action and the screen visibly reacting. It replaced First Input Delay as a Core Web Vital in March 2024:

• Good is under 200 milliseconds — slower than that and the page feels laggy or unresponsive, even if it loaded fast.
• It is measured across the whole visit — not just the first click, so a site that responds well on load but stutters later still scores badly.
• The cause is heavy JavaScript — too much script running on the main thread blocks the browser from reacting to taps.

INP is the hardest of the three to chase down because the cause is usually buried in scripts and third-party widgets. If your INP is poor, start by removing or deferring the scripts you don’t strictly need.