Interaction to Next Paint will officially become a Core Web Vital and will replace First Input Delay on March 12.
The Web Vitals program provides metrics to help web developers measure key aspects of the user experience on the web. First Input Delay (FID) represented the responsiveness aspect of the program, but over time, it became clear that a new metric was needed to capture aspects of interactivity on the web that FID did not. The Chrome team recognized this need, and introduced Interaction to Next Paint (INP) as an experimental metric in May 2022. Last year, INP became a pending metric, and we announced that INP would be promoted to stable status in March 2024.
Today, we're announcing that INP will officially become a Core Web Vital and replace FID on March 12 of this year, and that FID will be deprecated in this transition.
This post offers advice from the Chrome Team for how to prepare for this change, and what to expect once the changes take effect.
How can I prepare?
The first step in this transition is to figure out if your website's INP passes the "good" threshold. All Core Web Vitals are scored based on how well they perform in the field at the 75th percentile of all page loads.
The easiest way to see how your website is doing on INP is to use PageSpeed Insights, which surfaces data from the Chrome User Experience Report (CrUX). CrUX is the official dataset of the Web Vitals program, and may be a potential source of field data for your website.
Another source of field data may come from a Real User Monitoring (RUM) provider, which also observes your website's performance in the field. If you're working with a RUM provider, ask about their INP support.
If you find that your website's INP is either in the "needs improvement" or "poor" category, we've prepared several resources to help you improve it, beginning with how to diagnose and troubleshoot INP:
Once you know what the problem is, you can use the following guides to figure out which parts of the interaction you should optimize for:
- Optimize input delay if it's taking a long time for interactions to begin processing.
- Large DOMs can require a lot of rendering work, and interactions often change the DOM. It's best to avoid large, complex layouts and layout thrashing, and minimize DOM size where you can.
- If you have complex CSS selectors, they too can cause considerable work in response to user interactions.
INP's complexity means that you'll be optimizing for interactivity in many ways—but it's worth the effort. There have been several case studies done—such as those from The Economic Times and redBus—on how reducing interaction latency improves business outcomes. Optimizing INP on your site may help you to achieve your goals as well.
What will happen once INP becomes a Core Web Vital?
It's worth repeating that INP will officially become a Core Web Vital and replace FID on March 12 of this year. Another outcome of this is that FID will no longer be a Core Web Vital, and will be officially deprecated and removed from the program.
As a result, you can expect to see changes in FID documentation. Historically important documentation about FID will remain in place, but prominent notices will be added to stress FID's deprecated status, and to refer to INP documentation. Other FID-centric documentation may be removed altogether and redirected to relevant INP documentation.
FID is still represented in many of Google's tools, but so is INP. FID will be removed from Google Search Console as soon as INP becomes a Core Web Vital on March 12. All other tools—such as PageSpeed Insights and CrUX—will offer a six-month deprecation period to give developers a chance to update their code.
Finally, if you have any questions about what INP's inclusion in Core Web Vitals means for Google Search, refer to the INP announcement post on Google Search Central.
The road ahead
INP's inclusion in Core Web Vitals has been carefully planned over the last two years, and it represents a significant step forward. We believe that INP's holistic approach to responsiveness on the web will help developers to better assess and improve this important aspect of the user experience, and lead to a more responsive web over time. With INP set to become a Core Web Vital on March 12, we hope developers take this time to understand and optimize their INP performance.
As always, if you have questions or concerns, we welcome your feedback at email@example.com when it comes to INP, FID, or any other metrics in the Web Vitals program.