What is INP?

Understanding INP

INP means Interaction to Next Paint. It measures how quickly a page responds after interaction. Interactions include clicking a button or selecting a menu. They also include entering text or tapping a mobile control. INP measures the time until the browser shows the next visual update. It doesn't measure the time needed to load the whole page.

Related glossary terms: Core Web Vitals, Largest Contentful Paint, Cumulative Layout Shift.

INP replaced First Input Delay as a Core Web Vital in March 2024. First Input Delay measured only the delay before processing a visitor's first interaction. INP considers eligible interactions throughout the visit. A lower result usually means a page feels more responsive. The visual update must also show the requested action.

How INP Works, Is Measured, or Is Used?

For each eligible interaction, the browser records the delay before the next paint. This delay starts with the input event. It can include event processing and JavaScript execution. It can also include making and presenting the updated interface. INP usually reports the slowest meaningful interaction. It reduces the effect of extreme outliers. A single unusual event doesn't usually define the result.

Google evaluates INP using the 75th percentile of page visits. It groups visits by device type when enough field data exists. The current good threshold is 200 milliseconds or less. Results above 200 and up to 500 milliseconds need improvement. Results above 500 milliseconds are poor. Developers can investigate results with Chrome User Experience Report. They can also use PageSpeed Insights and browser performance tools. Teams can compare field data with controlled laboratory testing.

Why INP Matters?

INP matters because people judge pages by their reactions. A page can load its main content quickly but still feel broken. This happens when controls respond slowly after use. Examples include search boxes, navigation menus, filters, and checkout buttons. Poor responsiveness can increase errors, repeated clicks, abandonment, and frustration. This is especially true on mobile devices or slower hardware.

INP provides a useful technical signal for prioritising performance work. High values can point to long tasks or excessive JavaScript. They can also show expensive event handlers or inefficient making. Fixing these causes may improve usability. It may also support a more consistent experience. INP is only one part of technical quality. It doesn't replace content, accessibility, or search relevance.

When INP Matters Most?

INP deserves close attention on pages that need frequent interaction. Examples include ecommerce product filters, booking forms, and account areas. Other examples include web applications, calculators, and content-management interfaces. The metric is especially useful when analytics show repeated clicks. It also helps with incomplete forms and slow control responses. Teams can compare desktop and mobile behaviour.

Teams should assess INP after adding third-party scripts or large interface libraries. They should also check personalisation features and complex client-side functionality. A useful workflow starts by identifying the slow interaction. Next, inspect its event handler and main-thread work. Then reduce unnecessary processing and retest with suitable devices. SEO teams can combine field evidence with a technical audit. They shouldn't treat one laboratory score as proof of every visitor's experience.