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Core Web Vitals


Understanding INP vs FID: Unraveling Web Performance Metrics

Comparing Interaction to Next Paint & First Input Delay

James Gibbons
Interaction to Next Pant (INP) v/s First Input Delay (FID)

Are you wondering why Google is replacing First Input Delay (FID) with Interaction to Next Paint (INP) starting March 2024 in their core web vitals reporting? Curious about the differences between INP and FID and how they can help you develop seamless websites?

Let's take the mystery out of these metrics in this blog post. With a concise and clear explanation, you'll understand why Google's latest update is all about enhancing user experience. So, buckle up and prepare for a deep dive into INP vs FID and what this change entails.

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Google will Replace FID with INP in March 2024

As you might have heard, Google will be phasing out First Input Delay (FID) and replacing it with Interaction to Next Paint (INP) in March 2024. It will trigger a noteworthy shift in the Core Web Vitals assessment parameters. If you are unfamiliar with these terms, don't fear - let's break them down.

First Input Delay (FID) measures how responsive a web page is to user interactions. It calculates the time between a user's initial interaction (e.g., clicking a button) and the browser's response to that action. In simpler terms, FID assesses how fast a website reacts to user input, significantly impacting the user's page experience.

On the other hand, Interaction to Next Paint (INP) gauges how long it takes for a web page to become interactive after the initial page load. Rather than solely focusing on response delays, INP considers the time required to load essential interactive elements and scripts on the page. It offers a broader view of a website's responsiveness that helps improve user experience & SEO.

Learn more about Interaction to Next Paint (INP) & its impact on SEO in our comprehensive guide.

Why is Google Replacing FID with INP?

1. Limited Scope: FID focuses solely on measuring the delay between a user's initial interaction and the browser's response. It overlooks other important aspects of a website's interactivity, such as website load time, usability of the site, and how long it takes to become interactive.

2. Ignoring Load Time: FID does not consider the time it takes for essential interactive elements and scripts to load after the initial page load.

3. Inaccuracy for Modern Web Apps: FID does not reflect the UX of web applications, especially those with complex interactions & frequent updates. This limitation makes FID less suitable for assessing the performance of dynamic websites.

4. Single User Interaction: FID measures the delay for only one user interaction event. A single interaction delay may not capture the complete picture of a website's responsiveness.

While FID provides valuable insights into user interaction delays, INP offers a more comprehensive evaluation of a website's overall interactivity. By accounting for various factors influencing responsiveness, INP better reflects real-world user experiences.

Let us delve further into why this replacement is essential by examining the differences between the metrics.

How is INP Different From FID?

INP and FID measure user interaction and engagement on a webpage. However, they measure different aspects and have different implications. Here is how INP & FID are different:

Focus on User Experience

INP focuses on the time it takes from a user's interaction to the next paint (when the response from that interaction is processed and loaded on the screen). INP measures page responsiveness by analyzing quickly a user can see something happening after an interaction.

FID, however, measures page responsiveness from when a user first interacts with your site (click a link, tap on a button, etc.) to when the browser can respond to that interaction. This could be impacted by other processes the browser is conducting simultaneously.

Measurement & Score Implications

INP can be measured in lab environments, for instance, using testing tools that simulate user interactions and measure the reaction time.

A high INP score means the webpage takes longer to respond and reflect changes upon user interactions. This delay in visual feedback could be due to inadequate resources for rendering activity or inefficiencies in the rendering pipeline, leading to poor user experience.

FID, however, is a field metric and should ideally be measured in the context of real users interacting with your page, as it depends on real user devices and network conditions.

A high FID score means the browser takes longer to respond to the user's first interaction. This could be due to heavy JavaScript execution or other background tasks clogging the main thread.

Event Capturing vs. Visual Rendering

While both metrics provide valuable information about user experience, their underlying event-capturing mechanisms are distinct.

INP tracks events related to layout stability, such as image loading and element positioning, to determine visual stability. In contrast, FID focuses on interactions like clicks and taps, capturing the time to process these user actions.

Stages of Interaction

INP is concerned with the period from when user input is initiated to when the resultant visual response is rendered. This involves the entire process, the processing of the event, and even the painting of the response. INP indicates how quickly a webpage can respond to a user's action.

FID, however, is more of an early-input metric, timing from when a user first interacts with a site to when the browser responds to that interaction. It essentially measures the delay or any lag the user may experience. This gives a good reflection of the user's first impression of the site's interactivity.

Evaluation Perspective

INP provides a broader view of the user experience, analyzing the webpage's interactivity beyond the initial page load. It considers various elements and components contributing to overall interactivity, making it a more holistic metric for assessing user experience.

In contrast, FID's evaluation focuses only on the user's perception of responsiveness during the first interaction with the page. It captures the user's experience during the critical moment they first interact with the page, reflecting the web page's ability to respond immediately to the user's input.

Webpage Complexity

INP is particularly valuable for assessing user experience on complex web applications with multiple interactions and dynamic content. It helps developers identify potential bottlenecks that may affect overall interactivity and responsiveness.

FID's primary focus makes it relevant for websites with simple interactions or where user engagement heavily relies on immediate responses to their initial actions. For less complex web pages, FID offers crucial insights into the initial user experience, helping developers optimize the first interaction to create a positive impression.

Now that we understand the differences, we must also learn the similarities. Google is replacing FID with a new metric because it has some common ground with INP, which can provide a holistic approach.

What are the Similarities Between INP and FID?

1. Measuring User Interaction Time: A core similarity between INP and FID is their focus on measuring the time taken for a user’s interaction to receive a response.

2. Focus on User Experience: They both aim to quantify the quality of user experience on a webpage from the perspective of interactivity and responsiveness.

3. Detecting Delays: FID and INP work on detecting delays in interactive responsiveness. These metrics will tell developers exactly how long their site visitors might wait for their page to become interactive.

4. Mobile and Desktop Consideration: INP and FID are evaluated for mobile and desktop website versions. This consideration acknowledges the growing importance of mobile browsing and ensures that the page is optimized across devices.

The similarities between INP and FID do not negatively affect their roles; instead, they complement each other. Transitioning from FID to INP will allow developers to gain a more comprehensive understanding of user interactions & page interactivity. It will help foster a more user-friendly web ecosystem.

What is the Impact of INP Replacing FID on SEO?

This shift from FID to INP may impact your website's user experience & SEO performance. Google's algorithms prioritize websites that provide a better page experience to its users. Websites with fast and responsive interactivity, as measured by INP, are likely to receive better rankings in search results.

However, it is important to note that Google does not impose direct penalties for not meeting INP requirements. Instead, the consequences lie in user behavior. Websites with poor interactivity and slow INP times may experience higher bounce rates, and lower user engagement, affecting SEO & SERP rankings.

As INP takes over as the primary metric in Core Web Vitals, FID's role will change, but it will not be eliminated. FID will remain a metric that provides valuable information about user experience during the initial loading phase of web pages.

Moving From FID to INP

The transition from FID to INP as the primary metric has several business implications. This change emphasizes the importance of user interaction experiences, so businesses should invest in improving website design and content.

For developers, this means optimizing coding for faster interactivity and smoother visual transitions.

SEO/Marketers, meanwhile, should align their strategies with these performance metrics to improve website ranking and visibility in search engines.

Should You Still Optimize Your Website for FID?

Even after INP takes over, FID will still provide valuable insights into specific aspects of user experience during page loading. As such, website owners and developers should continue to track and optimize FID alongside INP.

Tracking FID can be particularly beneficial for websites with specific use cases where user interactions significantly impact conversions and engagement. Some scenarios where tracking FID remains important include:

1. E-Commerce Platforms: FID optimization is crucial for e-commerce websites with "Add to Cart" buttons or checkout processes, as slow response times can lead to cart abandonment and lost sales.

2. Lead Generation Pages: Websites with lead capture forms heavily rely on user interactions. Optimizing FID ensures a smooth experience, improving lead generation rates.

3. Interactive Web Applications: Web apps with real-time interactions, such as online collaboration tools or gaming platforms, require quick response times to enhance user experience and satisfaction.

Prepare for the Transition From FID to INP

The transition from FID to INP in Google's core web vitals metrics signifies a shift towards a more holistic approach to measuring webpage interactivity and responsiveness. Although FID has been an effective tool for assessing initial user experience, INP offers a broader perspective. It considers the time required to load essential interactive elements and scripts, thus offering a more realistic representation of real-world user experiences.

The shift could impact a website's SEO performance as Google prioritizes user experience. Therefore, website owners, developers, and SEO practitioners must understand and prepare for the changes. While the role of FID will be diminished with INP taking the forefront, it will still provide valuable insights into user experience during the initial webpage loading phase.

Web admins must develop strategies to optimize INP and FID effectively to enhance user experience and positively influence search engine rankings. You can leverage tools like Quattr & GSC to track & improve your INP & FID scores.

Transition from FID to INP site-wide easily with Quattr!

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Can both INP and FID be optimized simultaneously?

Yes, both INP and FID can be optimized simultaneously. While INP focuses on improving the responsiveness of a website to user interactions, FID aims to reduce delays in user input processing. Avoiding long tasks, unnecessary JavaScript, and large rendering updates, can help optimize both metrics, leading to enhanced web performance and superior user experiences.

What happens if my website does not meet the INP requirements after transitioning from FID to INP in March 2024?

If your website does not meet the INP requirements after the transition, it may experience negative impacts on its search rankings. Google prioritizes user experience, and poor INP scores could result in lower visibility and reduced organic traffic to your site. Therefore, optimizing for INP is crucial to ensure your website remains competitive in search results.

Can INP be affected by user behavior and device types, similar to First Input Delay?

Absolutely, user behavior and device type can significantly impact INP (Interaction to Next Paint). Factors like the way users interact with their devices, the frequency of use, and the device’s processing capabilities can influence INP. Similarly, high-end devices with advanced processors may experience less INP, providing a smoother user experience.

Will the replacement of FID with INP affect my current SEO rankings?

The replacement of FID with INP is expected to impact SEO rankings. It is recommended that website owners start preparing for this change by monitoring their site's performance using GSC & Quattr and start implementing any necessary updates to optimize for INP.

About The Author

James Gibbons

James Gibbons is the Senior Customer Success Manager at Quattr. He has 10 years of experience in SEO and has worked with multiple agencies, brands, and B2B companies. He has helped clients scale organic and paid search presence to find hidden growth opportunities. James writes about all aspects of SEO: on-page, off-page, and technical SEO.

About Quattr

Quattr is an innovative and fast-growing venture-backed company based in Palo Alto, California USA. We are a Delaware corporation that has raised over $7M in venture capital. Quattr's AI-first platform evaluates like search engines to find opportunities across content, experience, and discoverability. A team of growth concierge analyze your data and recommends the top improvements to make for faster organic traffic growth. Growth-driven brands trust Quattr and are seeing sustained traffic growth.

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