Understanding the New Core Web Vitals Metric: Interaction to Next Paint (INP)

When it comes to web development and search engine optimisation, usability metrics play a crucial role in assessing a site’s performance aiming to deliver a seamless user experience (UX). These metrics are part of Google’s Core Web Vitals (CWV) initiative to help improve how a webpage’s content loads with a focus on UX.

There are currently 3 metrics used in the assessment: Largest Contentful Paint (LCP), which measures loading performance, First Input Delay (FID), which measures interactivity, and Cumulative Layout Shift (CLS), which measures visual stability. However, FID has its limitations as it does not account for all forms of user input, such as scrolling.

Recognising these limitations, the Chrome team started experimenting with an alternative metric that would address these issues more effectively. This article delves into the Interaction to Next Paint metric, which is set to replace FID in March 2024, addressing the differences between FID and INP, revealing SEO industry insights, and outlining next steps for site owners, developers, and SEOs to help assist with this transition.

Core Web Vitals – Image Source: web.dev

Core Web Vitals – Image Source: web.dev

What are the Core Web Vitals (CWV)?


Core Web Vitals – Image Source: web.dev

Core Web Vitals – Image Source: web.dev

Core Web Vitals is a set of 3 performance metrics that measure how users interact with a website – how fast a website loads, how responsive it is to user interactions, and how stable the content remains when the page loads.

These performance metrics are primarily measured based on real users’ data, but simulations have been also used to analyse page load in a controlled environment.

These assessments produced an average performance that websites are graded against, and falling below the benchmarks set in the assessment can negatively impact SEO rankings.

What is the First Input Delay (FID)?

How FID Works – Image Source: product.webpagetest.org

The First Input Delay metric is looking at the time between user’s first click and browser response, e.g., clicking on a button or clicking on a sidebar as illustrated in the image above. The delay occurs if the browser cannot respond immediately to the user request due to other tasks still loading up.

FID is thus used for measuring the time it takes for the browser to respond to the first user interaction after the page has finished loading. It quantifies the delay between the user’s action and the browser’s ability to process that action, indicating how quickly the website becomes interactive and responsive to user input.

However, FID does not account for all forms of user input, such as scrolling, and it only measures the delay until the processing of user input begins, rather than the entire processing time. This is where the new metric, Interaction to Next Paint, comes into play.


What is the Interaction to Next Paint (INP)?

INP Progress – Image Source: developers.google.com

Interaction to Next Paint is a new update to Google’s CWV metrics, focusing on accurately measuring how long it takes users to interact with the site.

Although First Input Delay (FID) also looks at the interactivity, there are small tweaks to this new metric which improves it comparatively. INP is therefore introduced as a superior and all-encompassing metric for gauging responsiveness, providing a more accurate reflection of the actual user experience on a webpage compared to FID.

Like the Fist Input Delay metric, the Interaction to Next Paint strives to assist web developers and SEOs in their efforts to audit and optimise webpages, with the goal of enhancing page usability.

What makes INP better than FID in terms of performance evaluation?

Measuring Interaction to Next Paint – Image Source: corewebvitals.io

While FID – as the name states – focuses solely on the first interaction delay during the page load, INP offers a more comprehensive view of the whole user-page load interaction.

INP achieves this by analysing the longest interactions that occur when a user visits the page and then focusing on the interaction with the worst performing delay. This way, INP accurately measures the time users need to fully interact with the entire page.

Why is Google rooting for the Interaction to Next Paint vs First Input Delay?

It is hard to assess the reason the Chrome team concluded that FID did not achieve expected results, but it is safe to make the following assumptions based on CWV research:

  1. Out of the 3 Core Web Vitals metrics, FID was the only metric that most sites were successfully passing, while failing on both LCP and CLS. Analysing results that pointed to this issue must have made it clear for Google’s team that there is a lack of consistency in Google’s CWV metrics, and that more depth was needed to accurately assess user interactivity with a page.


  1. While for LCP and CLS there were equitable correlations between pages with high rankings and good Core Web Vitals assessment scores, this was not the case for FID scores – sites ranking on position 1 and position 9 were not showing big discrepancy in scores, as expected, but similar FID scores, which rendered FID fallible.


  1. Google frequently adjust their guidelines – reason for constant debates in the SEO community – but it is safe to assume that they do so with the genuine intention of enhancing the user experience for web browsers. Given the rapid pace of social media platforms, it becomes crucial for Google to ensure that websites, which are their primary focus, remain competitive. If people would find it easier to engage solely with social media, then Google would risk revenue loss.

Regardless of the reasons why Google changed the way they assess Core Web Vitals, focusing on improving interactivity to deliver the best user experience can bring numerous benefits to a business, as explained below.

Why is it essential to assess your site’s INP?

There is a direct relationship between favourable CWV metrics and reduced bounce rates, increased time-on-site, which lead to better UX with a positive impact on conversion rates as well as other crucial business key performance indicators (KPIs). This will apply to all users of the site, no matter which marketing medium they use to find and interact with the site.

By understanding the INP metric, SEOs and web developers gain the ability to monitor INP at both the site-level and page-level, while also examining how INP influences KPIs.

Relationship between CWV Performance and target KPIs

Page load time is a significant factor in search engine rankings and optimising it both site-wide and page-level would help improve performance leading to higher visibility and organic traffic. While looking at load time site-level helps spot potential issues that affect multiple pages using the same template or the entire site. Analysing load time at page-level helps in focusing efforts on optimising pages that are vital to user engagement and conversions.

While INP will become one of the 3 usability metrics used as SEO factors in the Web Vitals algorithm replacing FID, Google often considers Web Vitals a ‘tiebreaker’. If 2 different sites have good content on the same topic targeting the same keyword, but one of site’s passes the Web Vitals assessment, then this site may have a better ranking position and perform better in search.

However, passing Core Web Vitals is not as high a priority as investing time in key SEO cornerstones such as relevant content, especially after the development of Google’s Helpful Content Update.

What are the next steps in optimising towards a good Interaction to Next Paint?

Although Google will continue utilising FID instead of INP until March 2024, it is advisable to initiate the transition towards monitoring the INP metric as soon as possible. This is why Google have already started displaying how sites are performing with this metric. This shift is crucial not only because INP offers a more accurate UX assessment, but also because it reveals greater opportunities to improve page performance compared to FID.

Google’s comprehensive guide on Interaction to Next Paint outlines what an interaction is and what are the scores that webmasters should aim for:

Life of an interaction – Image Source: web.dev

Google also provides further documentation on how to optimise INP in preparation for the CWV change in March 2024. In the meantime, it is still recommended to keep track of FID as well, by aiming to keep it within a “Good” range – i.e., below 100ms – to maintain favourable performance.

What should webmasters expect next

Google will update you each month if you do not pass areas of this assessment. Site owners should expect to receive emails from Google Search Console notifying them if their INP scores did not meet the desired threshold.

Core Web Vitals Report – Image Source: Google Search Console Screenshot

However, while it is advisable to start assessing your INP score, there are no immediate changes taking place, as there are several months until INP would replace FID.

Optimising UX – where does INP fit in Google’s page experience algorithm?

Although INP will become one of the metrics that impact rankings in Google as of March 2024, it is worth painting the big picture of how the Core Web Vital metrics fit in the broader page experience algorithm.

Page Experience Search Signals – Image Source searchenginejournal.com

Metrics that are measuring page responsiveness represent just one component of the many aspects considered by the Google Page Experience algorithm when it comes to providing a good UX.

There are other metrics that are equally, if not more important when considering user experience (UX) and rankings. These include factors such as safe browsing, mobile friendliness, and making sure that no elements obstruct the page content. Which if not met a user may choose a competitor site that is offering a better, safer, and more enjoyable experience.

Core Web Vitals – and by extension Interaction to Next Paint – is Google’s way of assisting web developers and SEOs in creating user-centric pages and are not meant to be neglected as ranking factors. But like all of Google’s guidelines, improving a website is a matter of understanding what, how, and when to optimise.

Do you need expert assistance in optimising your website for the best Core Web Vitals metrics? If you want to discover more about how to enhance your website’s performance and user experience, do not hesitate to contact us today for SEO services or training.

Our team of professionals is here to help you achieve outstanding results. Contact Space & Time now to have a chat with our experts and unlock the full potential of your site online.