INP metric: Start using the new Core Web Vitals metric today!


Rich Bentley

July 6, 2023 | 4 min read

Last Updated: Jul 6, 2023

In May of 2023, Google announced a planned change to the Core Web Vitals (CWV) used to measure web performance. The new metric, Interaction to Next Paint (INP), will replace First Input Delay (FID) as the primary metric for measuring page interactivity. The reason for this change is that INP has been found to be a better, more comprehensive measure of responsiveness, and a better reflection of how users actually experience a page.

With its July release, Contentsquare now surfaces INP, allowing you to not only track the INP metric at both the site-level and page-level, but also to analyze the impact of INP on business outcomes like bounce rates, conversions, and revenues. (Note: For current Contentsquare customers, INP has been collected since April 25th, 2023, so you can start analyzing historical data immediately.)

Before we dive into what INP is and what you should do in response to this change, let’s quickly summarize Core Web Vitals in general and why they matter.

INP metric: Let’s do a Core Web Vitals overview

As most web developers, web performance and SEO practitioners know, Core Web Vitals are a set of three metrics that measure the real user experience for loading performance, interactivity, and visual stability of a web page.

Once the change from FID to INP metric is official in March of 2024, the three Core Web Vital metrics will be:

  • Largest Contentful Paint (LCP): Measures how long it takes for the largest content element on a page to become visible. LCP is important because it measures how quickly a user can see the main content of a page. If LCP is slow, users may lose interest and leave the page.
  • Interaction to Next Paint (INP): Measures the time between a user interaction and the next time the browser paints a new frame. The INP metric shows how quickly the page responds to user interactions. If INP is slow, users may have a poor experience resulting in frustration or confusion.
  • Cumulative Layout Shift (CLS): Measures the amount of visual change that occurs as a page loads. CLS is important. Why? Because it gauges how stable a page is as it loads. If CLS is high, the page may shift around as it loads, which can be disorienting for users.

For a more in-depth explanation of how each of these KPIs is calculated and what values of the metrics are good, needs improvement, and poor, see the Google Chrome Developer Relations team pages on LCPINP, and CLS. For the rest of this article, we’ll focus on why you should care about these metrics, and how to use them, including the new INP metric.

Why Core Web Vitals matter

Since May of 2021, Google has factored the Core Web Vitals (CWV) into their SEO ranking algorithm. All other things being equal, sites that score better on these metrics would rank higher.

That’s an important reason to care about CWV, but more importantly these KPIs reflect the reality of the experience of users on your site, and they have a big impact on business outcomes like conversion, bounce rates, and customer satisfaction.

A few real-world examples from the Google Chrome Developer Relations team:

  • Vodafone found that a 31% improvement in LCP led to 8% more sales, a 15% improvement in their lead to visit rate, and a 11% improvement in their cart to visit rate.
  • iCook increased ad revenue by 10% with a 15% improvement to CLS.
  • Yahoo! Japan increased page views per session by 15% and saw 13% longer session durations by optimizing CLS.

In our own customer base, we’ve seen strong evidence of the correlation between good CWV and stronger conversion level, revenues, bounce rates, time-on-site, and other key business KPIs.

INP metric introduction: What to do

So, what should you do differently with the introduction of INP?

First, if you’re not already, you should be monitoring all of the Core Web Vitals at both site-level and page-level to ensure the results fall into the “Good” range – less than 2.5 seconds for LCP, 0.1 or less for CLS, and less than 200ms for INP.

In the Contentsquare platform, you can now segment by INP, along with other performance metrics.

While FID will still be used by Google until March of 2024, you should start to transition to monitoring the INP metric as soon as possible, since it will provide a better representation of the actual experience of the user and will likely reveal more optimization opportunities than FID. You may want to continue monitoring FID in parallel, since it will still be used for search engine ranking, and try to maintain FID in the “Good” range of less than 100ms.

While monitoring the INP metric and the other CWVs is a good start, with Contentsquare you can go beyond just tracking to do deeper analysis and truly quantify the impact of web performance.

By segmenting and comparing users who experience a good INP to those who didn’t, you can understand the impact on things like:

  • Conversion rates: Did users with INP in the “Poor” or “Needs Improvement” range convert at a lower rate than those in the “Good” range? And what is the revenue implication on that difference?
  • Bounce rates: Were users more likely to bounce if their INP metric was not good?
  • User behavior: Did users experience frustration when INP was not up to snuff? Were they more likely to rage click? Did they interact differently with a page depending on INP?

With Contentsquare, it’s easy to compare users with good INP versus those with poor INP, and to quantify differences in conversion level, bounce rates, visit times, and other business KPIs.

Another way to use this type of segmentation is with Session Replay. Segment users with a “Poor” or “Needs improvement” INP and watch replays of those sessions to see exactly what’s happening. That can help to identify specific interactions that may be triggering a high INP, as well as helping you to understand how this is affecting user behavior.

While the INP metric is not available as a metric within synthetic monitoring (by definition), CS Speed Analysis Lab offers other metrics that can be monitored and used to proactively ensure interactivity and reduce the risk of poor INP, including Total Blocking Time (TBT), Max Potential FID, and Long Tasks Sum.

With Journey Analytics, you can visualize the difference in user journeys between those with a good INP metric result and those with poor INP.

Doing these types of analyses can help you understand the challenge, prioritize improvement efforts, and also demonstrate the value of your team’s efforts. Not only that, but you’ll also improve search engine rankings to drive business results.


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Contentsquare’s support for Core Web Vitals is part of our Digital Experience Monitoring solution. If you’re already using Digital Experience Monitoring, you have access to INP and the other CWV today. If not, contact us to get started understanding the impact of web performance on your business.