In 2024, Google officially introduced INP (Interaction to Next Paint) as part of its Core Web Vitals metrics – replacing the older First Input Delay (FID) metric.

INP measures how responsive a webpage feels when users interact with it — capturing the time between a user input (click, tap, or keypress) and the next paint of visual feedback on screen.

A strong INP score indicates that your User Experience (UX) and User Engagement are fluid and intuitive, which directly affects SEO and conversion performance.

Why INP Matters More Than FID?

Before INP, FID (First Input Delay) was used to measure responsiveness — but it only captured the delay before the browser began processing the first interaction.
FID ignored subsequent interactions and the visual feedback phase, offering a partial picture of responsiveness.

Key Limitations of FID

  • It measured only the first interaction after page load.

  • It didn’t include delays caused by JavaScript processing or paint updates.

  • It failed to represent user interactions that happened later in a session.

As a result, FID could not reflect the true Page Experience or how users perceive a website’s interactivity over time.
INP solves this gap by tracking the worst or near-worst interaction latency during the entire session, making it a more accurate metric for real-world performance.

How INP Is Defined & Computed?

2.1 Types of Interactions Measured

INP tracks these user interactions:

  • Mouse clicks

  • Taps or pointer events on touchscreens

  • Keyboard presses

It excludes scrolling and hovering unless they trigger a click or key event.
Each interaction is composed of multiple sub-events (e.g., pointerdown, click, mouseup) handled by the main thread.

2.2 Latency Components

Each interaction is measured from input to next paint, and divided into:

  1. Input Delay – waiting for the main thread to become available

  2. Processing Time – executing event handlers

  3. Presentation Delay – time until the visual frame is painted

This differs from FID because INP includes the paint phase, giving a complete view of perceived responsiveness.
If your site’s main thread is blocked by heavy JavaScript or third-party scripts, your INP will increase — indicating poor Technical SEO health.

How INP Handles Multiple Interactions?

On pages with many user interactions, INP does not simply take the worst single event — it uses a percentile-based approach (typically the 98th percentile).
This prevents rare spikes from distorting the metric and instead reflects a realistic user experience.
When aggregated across users, Google uses the 75th percentile of all page sessions as the official INP value reported in tools like Google PageSpeed Insights and Chrome User Experience Report (CrUX).

What Are Good and Bad INP Scores?

INP Value Category Interpretation
≤ 200 ms Good Excellent responsiveness – interactions feel instant
200–500 ms Needs Improvement Noticeable lag – may frustrate users
> 500 ms Poor Slow response – negative UX and SEO impact

High INP values often correlate with low Dwell Time and high Bounce Rate, since users are less likely to stay on a page that feels unresponsive.

Why INP Matters for SEO and User Experience?

Since March 2024, INP has been a ranking signal as part of Google’s Page Experience Update.
That means a poor INP can lower your Search Engine Ranking on the Search Engine Result Page (SERP).

A responsive site enhances the overall User Interface (UI), strengthens Core Web Vitals, and boosts metrics like Click-Through Rate (CTR) and Conversion Rate Optimization (CRO).

INP vs Other Web Vitals (LCP & CLS)

While INP focuses on interaction responsiveness, its sibling metrics — Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS) — measure different facets of performance.
Together, they represent the three pillars of web vital optimization:

  • LCP = Loading speed (how fast main content appears)

  • CLS = Visual stability (how much elements shift unexpectedly)

  • INP = Responsiveness (how quickly the page reacts to user actions)

All three are interconnected and critical for Technical SEO, User Experience, and overall Search Visibility.

How to Measure INP (Tools & Methods)?

Since INP represents a real-user interaction metric, accurate measurement requires field data, not just lab simulations.
Here’s how you can measure INP effectively:

a. Real User Monitoring (RUM)

Tools that capture data directly from real users provide the most reliable INP measurements.
These include Google Analytics 4 (GA4) integrations, Chrome User Experience Report (CrUX), and third-party RUM-based tools like SpeedCurve and Calibre.

RUM helps you see:

  • Which page elements trigger high latency

  • Which devices or browsers are most affected

  • How interactivity varies across page templates

These insights are critical for Technical SEO audits and long-term performance optimization.

b. Synthetic Testing Tools

You can also use lab tools to approximate INP behavior under controlled conditions.
The most popular include:

When combined with SEO Site Audits, these tools help pinpoint bottlenecks that lead to poor responsiveness and low engagement.

c. Lab vs Field Data

Lab data (from simulated tests) is ideal during development and staging, whereas field data (from live users) represents real-world performance.
To ensure accuracy, use a mix of both — lab data for controlled debugging, and RUM data for validating actual user experiences.

Common Causes of High INP

A high INP score indicates poor interactivity and delayed visual feedback. The most frequent causes include:

  1. Long JavaScript Tasks – Heavy code execution that blocks the main thread.

  2. Third-Party Scripts – Excessive analytics, ads, or widgets.

  3. Complex DOM Structures – Deeply nested HTML elements that increase rendering time.

  4. Inefficient Event Handlers – Bloated logic tied to clicks or keypresses.

  5. Layout Thrashing – Frequent reflows and repaints caused by poorly optimized CSS or DOM manipulation.

  6. Unoptimized Images or Fonts – Large media files delaying the next paint.

These issues often coexist with high Total Blocking Time (TBT), another metric reflecting main-thread congestion during load.

Optimization Strategies to Improve INP

Improving INP requires targeting each phase of the input → processing → paint pipeline.

1. Break Up Long Tasks

Divide heavy JavaScript operations into smaller asynchronous chunks.
Techniques like requestIdleCallback() or setTimeout() can prevent the main thread from locking up.
This directly enhances Page Speed and reduces Bounce Rate.

2. Use Web Workers

Offload expensive non-UI computations using Web Workers, freeing the main thread for interactivity.
This improves responsiveness and contributes positively to User Experience.

3. Prioritize Interaction Readiness

Defer non-critical scripts and use lazy-loading strategies for resources not essential to initial interactivity.
You can also apply Lazy Loading for below-the-fold assets.
Prioritizing above-the-fold interaction elements aligns with The Fold principles.

4. Optimize CSS and Layout Performance

Reduce costly layout recalculations by streamlining Cascading Style Sheets (CSS).
Use the Content Delivery Network (CDN) to serve assets faster and minimize render-blocking resources.
Combine and minify CSS and JS files wherever possible.

5. Limit Third-Party Scripts

Audit third-party tags using tools like Tag Manager and remove those that delay rendering or interaction readiness.
Each added script can increase latency, affecting INP and Core Web Vitals scores.

6. Provide Immediate Feedback

Show instant UI feedback — such as skeleton screens or spinners — when processing user actions.
Even if the full task takes longer, this improves User Engagement and perceived performance.

7. Reduce DOM Complexity

Simplify the document structure and avoid unnecessary re-renders, especially for Single Page Applications (SPAs).
A leaner DOM means faster paints and smoother interactions.

SEO and Business Implications of INP

a. SEO Ranking Signals

Since March 2024, INP officially replaced FID as part of Core Web Vitals.
This means it directly influences your Search Engine Ranking.
A page with a good INP score signals strong usability, helping you stand out in competitive Search Engine Result Pages (SERPs).

b. User Experience & Conversions

Improved INP enhances User Interface (UI) responsiveness and Conversion Rate.
Even small delays can reduce sales and form submissions — particularly on Landing Pages and checkout flows.
A faster, more interactive site lowers Bounce Rate and strengthens brand trust.

c. Business Impact

Good INP is not just a technical metric — it’s a business driver.
It directly affects:

Fast and interactive websites convert better, rank higher, and provide a more seamless digital experience — aligning with E-E-A-T principles.

Final Thoughts on Interaction to Next Paint

Interaction to Next Paint (INP) has redefined how we measure real-world web responsiveness.
By focusing on user-centric metrics instead of just page-load timing, INP bridges the gap between performance optimization and SEO strategy.
For modern websites, mastering INP is essential — not only for ranking but for retaining and delighting users in an increasingly experience-driven web.

Newsletter