How INP is measured#
INP observes every click, tap and key press during a visit and measures the delay until the browser paints the next frame — the moment the user sees a response. The reported value is roughly the slowest interaction (ignoring rare outliers on very interactive pages). It replaced First Input Delay (FID) as a Core Web Vital in March 2024 because FID only measured the first interaction.
Thresholds#
| Good | Needs improvement | Poor |
|---|---|---|
| ≤ 200 ms | 200 – 500 ms | > 500 ms |
The three parts of an interaction#
- Input delay: the main thread is busy with other JavaScript when the user taps.
- Processing time: your event handlers take too long.
- Presentation delay: rendering a large or complex DOM update takes time.
Common fixes#
- Remove or delay heavy third-party scripts (chat widgets, heatmaps, ad tags).
- Reduce plugin and page-builder JavaScript on WordPress.
- Break long tasks into smaller chunks and yield to the main thread.
- Give immediate visual feedback (e.g. show a loading state first, then do the heavy work).
- Keep the DOM smaller; avoid re-rendering large sections on every interaction.
Debug with Chrome DevTools’ Performance panel or the Web Vitals extension. Related: Core Web Vitals, third-party scripts, Core Web Vitals on WordPress.