INP (Interaction to Next Paint)
Interaction to Next Paint measures how quickly a page responds visually after a user taps, clicks or types. It replaced First Input Delay as a Core Web Vital in March 2024. A good score is 200 milliseconds or less, measured across the whole visit.
Why it matters for your rankings
INP is stricter than the metric it replaced. First Input Delay only measured the first interaction and only measured input delay, which meant most sites passed it easily and it revealed almost nothing.
INP measures every interaction throughout the visit and includes processing and rendering time. Sites that comfortably passed FID routinely fail INP, and the culprit is nearly always JavaScript: heavy third-party tags, unoptimised event handlers and long tasks that block the main thread while the user waits. This is the Core Web Vital most likely to be failing on a site nobody has audited recently, and it maps closely to the subjective feeling that a page is sluggish even though it loaded quickly.
How to check it on your site
Get field data
Search Console's Core Web Vitals report shows real INP. Lab tools cannot measure it properly because it needs actual user interaction.
Profile long tasks
In DevTools Performance, record an interaction and look for tasks over 50ms blocking the main thread.
Audit third-party scripts
Chat widgets, heatmaps, tag managers and ad scripts are the most frequent causes. Defer or remove what is not essential.
Break up heavy work
Split long JavaScript tasks with scheduler.yield or setTimeout so the browser can paint between chunks.