Interaction to Next Paint (INP)
TL;DR
INP measures how quickly a page responds to clicks, taps and key presses during the whole visit. Good is 200 ms or less at the 75th percentile; over 500 ms is poor. It replaced FID as a Core Web Vital in March 2024.
Explain Simply
You tap "Add to cart" and nothing happens for a second, so you tap again. INP is that wait. Under 200 ms, people do not notice it.
Interaction to Next Paint records the latency of every click, tap and keyboard interaction during a visit, from the input to the next frame the browser paints. The page's INP is its slowest interaction (on pages with many interactions, a near-slowest one, so a single outlier does not decide it). Google reports it at the 75th percentile of real visits: good ≤200 ms, needs improvement 200-500 ms, poor >500 ms.
INP became a Core Web Vital on 12 March 2024, replacing First Input Delay (FID), which timed only the first interaction and only its input delay.
INP exists only in field data: a lab test has no real user clicking. Lab tools use Total Blocking Time (TBT) as a stand-in, because long JavaScript tasks that block the main thread are the usual cause of both. Fixes: split long tasks and yield to the main thread, defer non-critical and third-party scripts, keep event handlers small, and move heavy work to web workers.
⚡Why It Matters
INP is one of the three Core Web Vitals in Google's page experience signal. A slow response makes a page feel broken: people tap twice, abandon forms, or leave.
🔍How CiteStat Checks
CiteStat shows the page's real-user INP from the Chrome UX Report (via PageSpeed Insights) under the scan result, with the share of visits rated good. The Performance score uses lab TBT as INP's stand-in.
CiteStat Score Impact
Field INP is shown, not scored. Lab TBT (≈INP) takes up to 2 points from the Performance category.
Fix Difficulty
Editor: N/A | Developer: Hard | AI Agent: Medium