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What is Interaction to Next Paint (INP)? Everything you need to know

Interaction to Next Paint (INP) is a new web performance metric introduced by Google to measure how quickly your website responds to user interactions. Starting March 2024, it will replace First Input Delay (FID) as one of the Core Web Vitals metrics that impact Google rankings.

In this simplified guide, we unravel the mystery behind INP, its impact on your ecommerce business, and how you can improve it for better web performance and user experience.

What is Interaction to Next Paint (INP)?

Imagine you’re browsing an online store, looking for the perfect shirt. You view a product page that has images, an item description and additional options. You like the color black, so you select this option. The images on the page are automatically updated to display your desired product in black. Now that you are satisfied, you click the add-to-cart button. This triggers a minicart popup showing the item you just added.

What is Interaction to Next Paint (INP)

The experience above basically sums up what Interaction to Next Paint (INP) is all about. The INP metric measures how quickly a webpage responds to your actions. In other words, this is the time that elapses between a click and the change in the page content (the “next paint”).

What are the user actions measured by INP? As far as INP goes, only the following interaction types are observed:

  • Clicking with a mouse.
  • Tapping on a device with a touchscreen.
  • Pressing a key on either a physical or onscreen keyboard.

Hovering and scrolling actions do not count.


The Interaction to Next Paint is a field metric (as opposed to the lab metrics analyzed by Google Lighthouse). This is because INP requires user input to measure, which is generally available in field data collected from real users.

The difference between INP and FID

INP looks at how long a user has to take in order to interact with the entire page. It generally takes into consideration the worst delay of any event that happens from a user interaction. However if there are many events or interactions, Google will measure the 98th percentile of longest interaction delays. 

This is a direct contrast to First Input Delay (FID) which only measures the first response delay from a user interaction (the first impression). 

Why does Interaction to Next Paint (INP) matter for ecommerce?

INP is directly related to page speed & page load time, which significantly impacts user behaviour. Having a low INP translates to tangible benefits: better user experience and lower bounce rates. It goes without saying that every second counts, and with INP, milliseconds.

Relationship between page load time and bounce rate - Think with Google

When your website responds quickly to a user’s click or tap, visitors are more likely to stick around, explore your products, and possibly make a purchase. A faster checkout process makes for greater conversions. Slow interaction times, on the other hand, frustrate users and drive them away. 

Additionally, Google’s introduction of INP as a new Core Web Vital metric in 2024 is a clear indication of how seriously it takes the metric into consideration when it comes to search rankings. So, a low INP not only keeps your visitors happy but also contributes to enhanced search engine visibility and conversions.

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How is Interaction to Next Paint (INP) measured?

INP measures the time between a user’s action, like a click or key press, and the next visible change on the page. This delay consists of three parts:

  • Input Delay: This is the time between user action and when the page starts to respond.
  • Processing Time: This is the time taken for the page to process the action and execute any related code or scripts.
  • Presentation Delay: This is the time between processing completion and the updated content appearing.

A good INP is under 200 milliseconds, showing quick responsiveness. On the other hand, an INP of over 500 milliseconds is considered poor.

How is Interaction to Next Paint (INP) measured and scored

Monitoring Interaction to Next Paint (INP) for your ecommerce

When it comes to INP (and other Core Web Vitals), real-time monitoring is crucial to ensure your ecommerce website performs optimally. Having the right monitoring tools help you detect issues affecting user interactions as soon as they arise, so that you can take immediate steps to resolve them. 

Here are two ways to monitor INP:

PageSpeed Insights: Google’s own tool provides insights into your website’s performance, including INP. While it is helpful, it only provides a current, one-time snapshot and doesn’t offer continuous monitoring.

Valido Web Score: The Valido Web Score app integrates PageSpeed Insights. In addition, Web Score provides real-time monitoring features through its interactive dashboards and visualizations. The app allows you to configure INP and Core Web Vitals tests across multiple webpages, devices, resolutions, and site locations. Also, Valido Web Score conducts regular monitoring of all the Web Vitals and Lighthouse performance metrics, allowing you to track your improvements and performance over time. 

Valido Web Score Monitoring Interaction to Next Paint (INP)

How to improve Interaction to Next Paint (INP) for your ecommerce

So now that you have an idea of what INP is and its impact on your ecommerce business, what can you do to improve it? Here are the top strategies that you can use to optimize INP:

Prioritize “above the fold” content: If rendering the contents for the entire page is slow, consider displaying only the important content first above the fold. This helps users see relevant information quickly and reduce the presentation delay part of INP.

Profiling website code and scripts: Analyze your website’s code and review third-party scripts. This helps identify performance bottlenecks and ensures your website responds faster to user actions.

Check the Total Blocking Time (TBT) to reduce background processing: The Total Blocking Time metric tracks how often there are background CPU tasks that could block other code from running. If the user interacts with the page while a background task is already in progress, then the browser first completes that task before handling the input event. Minimizing background processing helps to reduce the processing component of INP.

Asynchronous code execution: Use asynchronous code execution for swift UI updates. This ensures that users see immediate updates even while certain tasks are still ongoing.

Trim down code clutter. Use techniques like tree shaking to remove unused code and code splitting to bundle your code into smaller units that can load as needed. This helps improve the input delay part of INP.

Prioritize code execution: Revise your ecommerce website code so that less important code is loaded when the browser is not busy. One example is chat widgets, which is not necessary in the initial 500ms of a page load. This helps to prevent long duration tasks on the main thread, which mostly executes during the page startup phase and is often when a page is less responsive to user actions.

Make your page easy to render: This is probably one of the most effective tips when it comes to improving not just INP, but your overall website performance. Avoid large DOM sizes, too many or large images, too many videos or CSS animations, etc. This also helps to minimize the input delay.

Benchmark and track progress: As you apply the above strategies to enhance your Interactive to Next Paint (INP) speed, it is necessary to track the outcomes of these actions to ensure that they are improving the interactivity of your ecommerce website. Benchmarking your performance results is also critical so that you can see where you stand against the competition and if more improvements are needed.

Wrapping things up

Interaction to Next Paint (INP) is more than just a user experience metric; it is a critical factor that can significantly impact your website’s search rankings and conversions. By understanding how INP works as well as effective ways to monitor and optimize it, you can enhance the interactivity and user-friendliness of your online store, contributing to improved SEO and greater user satisfaction.

Alongside INP, there are also other performance metrics such as Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS) that also require monitoring and optimization for any ecommerce business. Valido Web Score provides you AI-powered insights into your ecommerce’s performance, and benchmarking features to ensure that you stay ahead of the competition.

Start monitoring and optimizing your website’s INP and other Web Vitals metrics with Valido Web Score. Get started today for free and elevate your website’s performance to the next level.