Interaction to Next Paint (INP)

Interaction to Next Paint (INP) is a metric that measures how quickly a Web site responds to user interactions such as clicks, taps and keystrokes. The score indicates how many milliseconds elapse between when a visitor performs an action and when the browser displays visual feedback. Google has been using INP as the official Core Web Vitals metric since March 2024, replacing First Input Delay. A low INP score means your website feels fast, a high score creates frustration and increases the likelihood of visitors dropping out.

How Interaction to Next Paint works and what it measures

INP measures the longest interaction delay during the entire visit to a page. Each time a visitor clicks, taps or presses a key, the browser initiates a series of actions: processing the event, executing JavaScript, adjusting the DOM and redrawing the screen. INP looks at the time between the user action and when the next frame becomes visible. Google takes not the average delay, but the 75th percentile of all interactions: the score experienced by 75 percent of your visitors. A score below 200 milliseconds is good, between 200 and 500 milliseconds should be better, above 500 milliseconds is bad. In practice, for SME websites, we often see scores between 300 and 800 milliseconds, especially on mobile and for pages with a lot of JavaScript.

Why Google introduced INP and replaced First Input Delay

First Input Delay only measured the very first interaction on a page and only looked at processing time, not visual feedback. This gave an incomplete picture: a visitor could click ten times and experience a slow response nine times, but the FID score remained green. INP measures all interactions during the visit and takes into account the full cycle until the browser shows something. That makes the metric much more representative of perceived speed. Google announced the change back in 2022 and officially made INP part of the Core Web Vitals in March 2024. Websites that score well on INP get a slight ranking boost; poor scores can cost visitors and conversions.

What makes a good INP score for SME websites

A low INP score ensures that your website feels responsive right away. Visitors click a button and see immediate feedback, which helps them maintain trust and click through to the next step. For ecommerce stores, we’ve observed that an improvement from 400 to 180 milliseconds can reduce the abandonment rate in the checkout process by 8 to 12 percent. For B2B websites with forms or configurators, a good INP is essential: if a visitor selects an option and nothing visible happens, they’ll think the site is broken. A well-thought-out SEO strategy always takes Core Web Vitals into account, because Google factors speed and user experience into its rankings. You can monitor your INP score via Google Search Console and PageSpeed Insights, where you’ll also receive specific recommendations for improvement on a per-page basis.

INP is especially valuable for pages where visitors are actively performing actions: filling out forms, filtering products, opening menus or scrolling through content. Here are four concrete situations where INP makes the difference between a fluid experience and a slow, frustrating website.

Ecommerce stores with filters and product configuration

In an ecommerce store, visitors use filters to select products by size, color, price or stock. Each click on a filter option triggers JavaScript that updates the product list. If that update takes 600 milliseconds, the ecommerce store feels slow and visitors drop out. A good INP score below 200 milliseconds ensures that the new product list appears almost immediately. For ecommerce stores with 500 to 2,000 products, we often see heavy JavaScript libraries or unoptimized database queries pushing up the INP. By processing filters server-side or applying lazy loading, you can improve the score by 40 to 60 percent. This leads directly to more product page visits and higher conversion rates because visitors find what they are looking for faster.

Forms and lead generation pages.

On contact forms, quote requests or sign-up pages, every entry should provide immediate feedback: a check mark for a correctly filled out field, an error message for an incorrect e-mail address or a tooltip for a required field. If that feedback appears only after 400 milliseconds, the visitor does not know whether his entry has been registered and fills out the form twice or clicks away. A low INP provides instant validation and a sense of control. For B2B websites with multi-stage forms, we find that improving the INP score from 500 to 180 milliseconds increases the number of completed forms by 15 to 20 percent. Technically, you achieve this by doing validation client-side with lightweight scripts and loading heavy third-party tracking only after submission.

Mobile websites with hamburger menus and accordions

On mobile, visitors tap a hamburger menu, a drop-down menu or an accordion to see more content. If the menu only opens after 500 milliseconds, they tap again and get irritated. A good INP score under 200 milliseconds causes the menu to open immediately. Mobile browsers often have less computing power than desktop, so JavaScript-heavy interactions take longer. By using CSS animations instead of JavaScript animations and by slowing down third-party scripts with async or defer, you can reduce INP on mobile by 30 to 50 percent. This is crucial, since more than 60 percent of SMB website visitors come via mobile and Google indexes mobile-first.

Dashboards and applications with real-time data

In dashboards or Web applications, users click on tabs, charts or date filters to view data. If the graph updates only after 700 milliseconds, the application feels unwieldy and users trust the data less. A low INP ensures that the interface is instantly responsive, even for complex calculations. In practice, we see that dashboards with a lot of data fetching and rendering often have INP scores above 600 milliseconds. By preloading data, applying virtual scrolling and moving heavy calculations to an API, you can bring the score down. That improves the user experience and increases the likelihood that users will return daily.

When Interaction to Next Paint is the right focus and when it is not

INP is relevant to any website where visitors are actively performing interactions: clicking, tapping, typing or scrolling. If you have a Web site with mostly static content and few interactive elements, then Largest Contentful Paint or Cumulative Layout Shift is more important. But once you have forms, filters, menus or configurators, you need to prioritize INP. You improve a good INP score by optimizing JavaScript, deferring third-party scripts and handling interactions server-side or with light client-side code. Start with the pages that generate the most traffic and conversions, because that's where an improvement will have the biggest impact.