Interaction to Next Paint, the new Core Web Vital coming in 2024

On May 10, 2023, Google announced that a new metric, Interaction to Next Paint (INP) will replace First Input Delay (FID) as part of the Core Web Vitals in March 2024.

The general idea is that a web page should respond quickly to user inputs — clicks, taps, and keyboard interactions — and both of these metrics are designed to measure just how “zippy” the page feels.

However, there’s a difference in what each metric measures and the scope of what each tracks.

A meme of an adorable pug dog looking at a treat on a table, with the text Interaction to Next Treat.

TL;DR — INP is a “tougher” measurement than FID — but there’s no need to panic! It won’t be a ranking factor until March 2024.

We’re seeing that ads can contribute to INP, so we’ll be looking forward to seeing how the ad networks will optimize their scripts for improvements. In the meantime, there are some general ways to improve your site’s INP, including:

  • Dialing back the amount of JavaScript on your site (usually by reducing the number of plugins that add features to your pages)
  • Reducing the size of your web pages (paginating comments, reducing drop-down menus, etc.)
  • Avoiding large, complex layouts

The Difference Between FID and INP

FID measures only the user’s first interaction on a page (hence “First Input”). Since Core Web Vitals were launched, Google has found that the vast majority of sites are already in the “Good” range for this metric, so it has turned out not to be all that useful for differentiating “good” from “bad.”

INP, on the other hand, considers all of the user’s interactions during their entire visit to a web page, making it a better overall reflection of how responsive a page is, and therefore a better indicator of Page Experience.

Additionally, FID only measures the delay portion of a user’s interaction with the page, while INP measures the time from the start of the interaction through when the browser shows a change (when it “paints” the next frame…hence “Interaction to Next Paint.”)

The INP measurement that’s reported, then, is the longest single interaction time observed during an entire page view (ignoring outliers).

What’s a Good INP Score?

As with the other Core Web Vitals, Google uses the 75th percentile of page loads as the threshold — meaning that only 75% (or more) of page loads need to be “Good” for the URL itself to be considered “Good.”

In real numbers, an INP at or below 200 milliseconds falls into Google’s “Good” range. An INP between 201 and 500 milliseconds gets flagged as “Needs Improvement,” with times greater than 500 milliseconds falling in the “Poor” range.

Interaction to Next Page Ranges illustrated with a bar graph

When to Start Worrying About INP (not yet!)

INP won’t replace FID as an official part of Core Web Vitals until March 2024.

In preparation for this change, Google PageSpeed Insights (GPSI) displays real-world INP data for sites in the Other Notable Metrics section of the GPSI report:

PageSpeed Insights report highlighting the Interaction to Next Paint (INP) metric in the Other Notable Metrics section.

You can check how your site’s currently faring for INP by testing it with PageSpeed Insights.

INP is also now incorporated into the Core Web Vitals reports in Search Console. When viewing either the Mobile or Desktop reports, if you scroll to the bottom, you may see a section called Prepare for changes coming in March 2024 letting you know that INP Needs Improvement or is Poor on some of your pages.

Google Search Console Core Web Vitals Mobile report showing new section called Prepare for changes coming in March 2024 which shows pages that need INP improvements.

If your PageSpeed Insights or Search Console reports show your INP metrics are in the “Needs Improvement” or “Poor” range, there’s no cause for panic. As with the initial rollout of Core Web Vitals, Google has given everyone advance notice of the launch of INP, so there’s still time to optimize and make improvements.

So, while now is a good time to start addressing any issue with INP and getting those numbers into the Good range, the situation isn’t urgent. 😎

How to Improve INP

Since INP is tracking how long it takes after the user clicks, taps, or presses a key until the browser shows a change (sidenote: In general, scrolling is not included in this metric), our goal is to reduce the amount of “work” the browser has to do when someone interacts, so we can reduce any sluggishness for the visitor.

In other words, the more “thinking” the visitor’s device has to do, the slower response will be — and too slow a response will result in a poor experience.

General Ways to Optimize for INP

Like the other Core Web Vitals where many factors come into play (particularly CLS), optimizing for INP can lead deep into the weeds. Nevertheless, here are some general ways you can start optimizing your site for better INP before March:

  • Reduce assets like unnecessary JavaScript and CSS. For WordPress sites, this often means removing plugins and features you don’t need. For example if you’ve got three or four different newsletter opt-in elements (popups, multiple embedded forms, etc.) figure out which ones actually get the most sign-ups and ditch the rest.
  • Avoid large, complex layouts. Complex layouts with more elements require more processing by the browser to render or re-render during interactions. (Another good reason to avoid page builders.)
  • Minimize DOM size. In simple terms, the DOM is the number of elements or amount of “stuff” on the page. A large DOM requires more work to render initially. And, in response to user interaction, that can cause rendering updates to increase the time it takes for the browser to re-draw the page. Some ways to reduce DOM size include minimizing drop-down menus, reducing the levels of nested comments, and enabling comment pagination.

The Effects of Ads on INP

In recent months, we’ve tracked the INP metrics of more than 800 sites daily. When we compared the overall INP metrics for sites with ads and those without, it’s clear that running ads correlates to sites with much higher INP. This makes sense, as JavaScript generally drives ads and can bog down a browser.

We’ve already seen a gradual improvement in the overall INP for several networks, which is a reassuring trend:

Charts showing a comparison of cumulative INP for various sites with ads from various unnamed ad networks versus sites with no ad network

Our team has been in contact with the largest ad networks, and their engineers are already looking into the impact of their scripts on INP and ways to address any issues. Ultimately, if your site is running ads, a lot of the ‘heavy lifting’ for improving INP will likely be done by your ad network.

Learn More

We’ll be continuing to track INP closely as we go forward, and as this continues to evolve, we’ll keep our clients informed about any changes that may need to be made.

In the meantime, if you want to learn more, here are a few other resources:

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