What is Interaction to Next Paint (INP)?
INP measures how quickly a page responds to clicks, taps and key presses. Good is 200 ms or less. It replaced FID as a Core Web Vital in 2024.
Updated
Interaction to Next Paint (INP) measures how quickly a page visibly responds when someone clicks, taps or presses a key. It takes roughly the slowest interaction during a visit and times it from the input to the next frame the browser paints. A good INP is 200 milliseconds or less; over 500 milliseconds is poor.
Why did INP replace FID?
First Input Delay only measured the delay before the browser started handling the first interaction. INP covers every interaction in the visit and the full time until the screen updates, so it catches the sluggish menus and filters people actually notice. INP became a Core Web Vital on March 12, 2024, replacing FID.
What makes INP slow?
- Long JavaScript tasks running on the main thread when the user interacts, often from third-party scripts.
- Event handlers that do heavy work before letting the browser paint.
- Very large pages (DOM size) that take long to re-render after a change.
How do you improve INP?
- Break long tasks into smaller ones and yield to the main thread between them.
- Show visual feedback first, then do the slow work after the next paint.
- Remove or defer third-party scripts you don’t need.
- Keep the DOM smaller and avoid re-rendering the whole page for a small change.
Example
On a store’s category page, tapping “Sort by price” freezes for 700 ms while a script re-sorts and re-renders 300 products. Showing a loading state immediately and sorting in smaller chunks can bring the interaction under 200 ms.
Field INP comes from real Chrome users (CrUX), shown in Search Console and PageSpeed Insights. Related: LCP, CLS.