Interaction to Next Paint (INP)
Also known as: INP, responsiveness web vital, interaction to next paint
Interaction to Next Paint (INP) is a Core Web Vital that measures how quickly a page visually responds to user interactions (taps, clicks, key presses). It reports the worst interaction latency over a visit; a good score is 200 ms or less.
- Good INP is 200 ms or less; poor is above 500 ms, at the 75th percentile of real users.
- INP replaced First Input Delay (FID) as a Core Web Vital in March 2024.
- Latency breaks into input delay, processing time, and presentation delay — main-thread blocking is the usual culprit.
How INP is measured
INP observes every qualifying interaction during a page visit — clicks, taps, and keyboard inputs — and measures the full latency from the user's input to the next frame the browser paints to the screen. Hover and scroll are excluded.
Each interaction's latency spans three phases: input delay (time before event handlers can run, often because the main thread is busy), processing time (running the event handlers), and presentation delay (recalculating layout and painting the new frame). INP reports roughly the worst interaction from the visit, ignoring rare outliers on pages with many interactions.
Thresholds and what hurts the score
Google rates INP as good at 200 ms or less, needs improvement up to 500 ms, and poor above 500 ms, measured at the 75th percentile of real users in the Chrome User Experience Report (CrUX). INP replaced First Input Delay (FID) as a Core Web Vital in March 2024.
Long JavaScript tasks that block the main thread are the most common cause of poor INP. Breaking up long tasks, deferring non-critical work with requestIdleCallback or yielding, and minimizing layout-triggering DOM changes during interactions all reduce latency. Tools like Lighthouse, PageSpeed Insights, and the web-vitals JavaScript library report field and lab INP.