Interaction to Next Paint (INP) measures responsiveness. It observes the delay between a user interaction (a click, tap or key press) and the next frame the browser paints, across the whole visit, and reports one of the slowest. INP replaced First Input Delay as a Core Web Vital in March 2024.
| Rating | INP (75th percentile) |
|---|---|
| Good | 200 ms or less |
| Needs improvement | 200 ms to 500 ms |
| Poor | Over 500 ms |
INP in lab tests
INP needs real interactions, so it comes from field data such as CrUX. A standard Lighthouse page load does not measure it. Total Blocking Time is the closest lab signal: a page with a busy main thread during load is likely to respond slowly too.
How to improve it
Break up long JavaScript tasks, defer non-essential third-party scripts, keep event handlers small, and avoid large synchronous re-renders after an interaction.