Technical SEO
Interaction to Next Paint (INP)
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What is Interaction to Next Paint (INP)?
Interaction to Next Paint (INP) measures a page's responsiveness to user interactions throughout its entire lifecycle — not just at initial load. It captures the latency of all click, tap, and keyboard interactions and reports the worst-case interaction duration, excluding outliers. INP replaced First Input Delay (FID) as a Core Web Vital in March 2024. A score of 200 milliseconds or less is "Good," 200–500ms "Needs Improvement," and above 500ms "Poor."
Poor INP is typically caused by long JavaScript tasks on the main thread that block the browser from responding to user input. Optimization strategies include breaking long tasks into smaller chunks using scheduling APIs, reducing JavaScript execution time, and deferring non-critical third-party scripts. Unlike FID, which only measured the first interaction, INP provides a more comprehensive picture of interactivity throughout the entire page session.
Why it matters for SEO
INP is the Core Web Vital that most directly reflects how responsive a page feels during real use — not just at load time. Poor responsiveness frustrates users and signals low interactivity quality to Google, making it a critical metric for both user experience and ranking performance.
Example
On a travel booking site, tapping "Search flights" on a mid-range phone freezes the page for nearly a second while a large JavaScript bundle runs, before any spinner appears. Showing the loading state immediately and moving the heavy work into smaller chunks (or a web worker) lets the page respond to the tap right away, improving INP.
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