INP Core Web Vitals: What You Need to Know

User experience (UX) is crucial. Google has long emphasised that websites must be fast, responsive, and user-friendly to rank well in search results. To help website owners and developers understand and improve their site’s performance, Google introduced Core Web Vitals — a set of specific metrics that focus on real-world user experience.

Recently, Google announced a new addition called INP, which stands for Interaction to Next Paint. INP is set to become a vital part of Core Web Vitals, focusing on how quickly your website responds to user interactions. In this article, we will break down everything you need to know about INP Core Web Vitals, why it matters, and how you can improve your website to meet these new standards.

What Are Core Web Vitals?

Before diving into INP, let’s quickly understand what Core Web Vitals are.

Core Web Vitals are a set of metrics introduced by Google to measure the user experience on websites. They primarily focus on three aspects:

1. Loading – How fast does the website load and display content?
2. Interactivity – How quickly can a user interact with the website?
3. Visual Stability – Does the content move around unexpectedly while loading?

The original three Core Web Vitals metrics are:

• Largest Contentful Paint (LCP): Measures loading performance, i.e., how long it takes for the largest visible content (like images or text) to load on the screen.
• First Input Delay (FID): Measures interactivity, i.e., the delay between when a user first interacts with the page (click, tap, etc.) and when the browser responds.
• Cumulative Layout Shift (CLS): Measures visual stability, i.e., how much the page layout shifts during loading.

Google uses these metrics to judge your website’s user experience and includes them as ranking signals. That means better Core Web Vitals scores can help your website rank higher in Google Search results.

What is INP? (Interaction to Next Paint)

INP stands for Interaction to Next Paint. It is a new performance metric introduced by Google to replace or supplement the existing First Input Delay (FID).

Why the Change?

While FID was useful, it had limitations. It only measured the delay for the first user interaction and did not consider interactions after the page was fully loaded. Many users interact with pages multiple times, and FID failed to reflect the overall interactivity experience.

INP, on the other hand, measures the latency of all interactions on a page, giving a more comprehensive view of how responsive a website is throughout the entire user session.

How Does INP Work?

INP measures the time between a user interaction (like a click, tap, or key press) and the next time the browser visually updates the page to reflect that interaction. This time gap includes the processing delay and the rendering delay.

Simply put, INP tracks how long it takes for the website to respond visually after a user interacts with it. This can include button clicks, form submissions, scrolling, or any other interactive element.

What Makes INP Different?

• It accounts for all interactions on the page, not just the first.
• It captures the worst interaction delay experienced by users during their session.
• It provides a more realistic measure of website responsiveness over time.

Why Is INP Important?

In today’s digital landscape, users expect websites to be fast and highly responsive. If a site takes too long to respond to clicks or taps, users get frustrated and may leave the site altogether, leading to high bounce rates and lower conversions.

INP reflects the actual responsiveness users experience throughout their visit, making it an essential metric for:

• Improving user experience: Responsive websites keep users engaged.
• SEO benefits: Google has confirmed that INP will be part of Core Web Vitals and impact rankings.
• Business goals: Faster response times can lead to better user retention and higher sales.

How is INP Measured?

INP measures the latency between the user’s interaction and the next time the page visually updates.

The interactions tracked include:

• Mouse clicks
• Keyboard inputs
• Tap or touch gestures
• Other input types like pointer events

Google records the latency for each interaction during the page session and reports the worst latency as the INP score.

What Are the INP Score Thresholds?

Like other Core Web Vitals metrics, INP has thresholds to indicate performance quality.

• Good: INP less than 200 milliseconds
• Needs Improvement: INP between 200 ms and 500 ms
• Poor: INP more than 500 milliseconds

A good INP score means users experience quick, smooth responses to their interactions. Scores above 500 ms suggest sluggish interactivity that can frustrate users.

How Does INP Affect SEO?

Google officially announced that INP will replace FID as the Core Web Vital metric for interactivity in May 2025. This means that website owners should start focusing on improving INP to maintain or improve their search rankings.

Since Core Web Vitals are part of Google’s page experience signals, a poor INP score can affect your:

• Google search rankings
• Visibility in mobile and desktop searches
• User engagement and retention

How to Measure INP on Your Website?

You can check your INP score using various tools:

1. Google PageSpeed Insights

PageSpeed Insights now includes INP as part of the Core Web Vitals report. Enter your URL, and you will see your INP score along with other metrics.

2. Chrome User Experience Report (CrUX)

CrUX provides real-world user data, including INP, gathered from actual Chrome users.

3. Chrome DevTools

In the Performance panel, you can simulate interactions and measure latency.

4. Web Vitals JavaScript Library

Developers can integrate this library to measure INP on their websites programmatically.

How to Improve Your INP Score?

Improving INP requires optimising how quickly your website responds to user interactions. Here are some actionable tips:

1. Minimise Main Thread Work

The browser’s main thread handles user interactions, script execution, and rendering. If it’s busy running heavy JavaScript, user input events are delayed.

• Break long JavaScript tasks into smaller chunks.
• Use Web Workers to offload non-UI tasks.
• Remove unused JavaScript and third-party scripts.

2. Optimise JavaScript Execution

Heavy JavaScript slows down the browser. Optimise by:

• Using code-splitting and lazy loading.
• Avoiding blocking synchronous scripts.
• Using modern JavaScript frameworks that optimise runtime performance.

3. Use Efficient Event Handlers

Make sure event handlers respond quickly:

• Avoid heavy computations inside event listeners.
• Debounce or throttle expensive event handlers.

4. Avoid Long Tasks

Long tasks block the main thread and delay interactivity.

• Identify long tasks in browser DevTools.
• Optimise or split them.

5. Prioritise User Input Handling

Make input processing a priority by:

• Using passive event listeners where possible.
• Avoiding unnecessary UI updates on input events.

6. Optimise Rendering and Painting

Reducing layout thrashing and complex rendering helps faster visual updates:

• Minimise layout shifts.
• Use GPU-accelerated CSS animations instead of JavaScript.

Common Challenges While Improving INP

• Heavy third-party scripts: Ads, analytics, and chat widgets can add processing time.
• Legacy codebases: Older websites may not be optimised for modern performance standards.
• Complex UI interactions: Websites with complex animations or dynamic content may find it challenging to keep latency low.
• Mobile devices: Lower-powered devices often struggle with interactivity, so testing on mobile is critical.

Future of Core Web Vitals and INP

Google’s Core Web Vitals are evolving to better reflect the real user experience. INP is a step forward, providing a more comprehensive measure of responsiveness.

As Google updates its ranking algorithms, INP will play a significant role. Website owners, developers, and digital marketers must stay updated and optimise for these metrics to ensure:

• A better user experience
• Higher search rankings
• Improved business results

Conclusion

INP Core Web Vital is a vital new metric that measures how responsive your website is to user interactions. Unlike the earlier FID metric, INP captures the latency for all interactions during a user’s session, offering a more complete picture of your site’s interactivity.

For website owners and developers, focusing on INP means improving JavaScript efficiency, optimising event handling, and reducing main thread blocking. With Google making INP a key ranking factor, you cannot afford to ignore it.

Regularly monitor your INP scores using tools like Google PageSpeed Insights and Chrome DevTools, and take necessary steps to improve responsiveness. By doing so, you ensure a smoother user experience, higher user engagement, and better SEO rankings — all essential for succeeding in today’s competitive online world.