Interaction to Next Paint (INP)

The metric that may replace First Input Delay in Core Web Vital reports

By
James Gibbons

Google introduced a new metric for page experience called Interaction to Next Paint (INP). INP is an experimental field metric that measures responsiveness. Responsiveness is how fast a page responds to user inputs and is thus a critical metric for tracking user experience scores.

Google puts a lot of emphasis on improving user experience.

The Core Web Vitals update rolled out last year is proof that user experience is a key ranking factor for Google. There is a lot of chatter about if and when INP will replace FID (First Input Delay) to become a Core Web Vitals tracking metric.

While the replacement is still not finalized, let us look at and understand this new metric and learn how we can improve our website’s performance score for Interaction to Next Paint (INP).

What Is Interaction To Next Paint (INP)?

Interaction to Next Paint (INP) is a field metric that measures page responsiveness. A page is considered responsive if it responds to user input quickly.

Interaction to Next Paint (INP) diagram
How Interaction to Next Paint (INP) works?

INP is particularly useful for measuring the responsiveness of a web page as it does not require any JavaScript or CSS code, unlike some other metrics. Instead, it measures only how fast the browser displays elements on the screen after receiving user actions.

Google Webmasters blog post on page responsiveness mentions that INP is an experimental metric and will be available in Google Search Console (GSC) as “Page Experience” under the “Site Performance” section. However, currently, GSC shows FID (First Input Delay) under Site Performance instead of INP. So there is no way to get this data right now via GSC.

It is, however, currently live when checking a page’s score through Google’s PageSpeed Insights tool. Upon testing various URLs across different websites, the INP score can vary dramatically from the more traditional FID score. In cases where a website may be well-optimized towards FID and report a “good” score for this metric, the Interaction to Next Paint (INP) metric may be vastly different and unveil some additional implementations needed before scoring well there.

Interaction to Next Paint (INP) & FID metrics in Core Web Vitals Report
INP & FID metrics in Core Web Vitals Report

Why is Interaction to Next Paint (INP) a field metric?

A field metric is a measurable factor or characteristic used to assess a specific field's performance. A field metric requires user input to measure which is collected from real users.

Interaction to next paint is a field metric because it measures how quickly a user can interact with the next element on the page after the current element. This metric is important because it can help to gauge how smoothly the website is running and how quickly users can navigate through the pages.

Advantages of Interaction to Next Paint (INP)

1. It helps measure how fast a page responds to user inputs without any JavaScript or CSS code, as some other metrics do. It can be used for both mobile and desktop sites which makes it more universal than FID (First Input Delay).

2. It works across devices and browsers, which means that even if your website looks good on Chrome but not on Firefox, you can still measure its responsiveness using INP, as this metric does not depend on JavaScript or CSS code executed by browsers but just measures how fast your browser responds to user inputs without any external factors like network latency and rendering.

3. It can be used to measure the responsiveness of your homepage and any page on your website, especially pages that could have a lot of interactivity.

Drawbacks of Interaction to Next Paint (INP)

1. It is not supported by any third-party service right now. So if you want to use it, you will have to implement it yourself.

2. It depends on the Google Chrome browser, so if you want to get this data for your website, you will have to use Google Chrome as your primary browser (if you don’t already).

3. Even though it measures how fast a page responds to user inputs without any external factors like network latency and rendering, there still might be some internal factors that cause delays in the responsiveness of a page that INP does not measure. For example, suppose a webpage has JavaScript code that loads many resources from other domains (like ads or widgets). In that case, this could cause delays in that web page's responsiveness even though it responds quickly to user inputs without any external factors like network latency and rendering.

4. As mentioned above, there is no way to get this data site-wide via Google Search Console (GSC) due to FID (First Input Delay). Websites will have to check for this through the PageSpeed Insights tool manually. Hopefully, Google will begin to include INP in GSC soon or at least provide some way for webmasters and SEOs to access this data through GSC/Search Console API shortly so they can start measuring their websites’ responsiveness using this metric from a broader view, especially once this officially becomes an official Core Web Vitals metric.

What is a Good Interaction to Next Paint (INP) Score?

Interaction to Next Paint (INP) is measured in milliseconds, and it measures the time taken for a page to respond to the first input after a user action, like clicking a link or button.

According to Google, an INP below or equal to 200 milliseconds indicates good responsiveness. An INP above 200 milliseconds and below or at 500 milliseconds means that your page's responsiveness needs improvement. An INP above 500 milliseconds implies that your page has poor responsiveness.

Interaction to Next Paint (INP) measurement metrics
Interaction to Next Paint (INP) measurement metrics

How is Interaction to Next Paint (INP) different from First Input Delay?

Interaction to Next Paint (INP) is the delay that is introduced by the input buffer, while First Input Delay is the delay that is introduced by the first stage of the pipeline. INP is more than about first impressions as it represents the amount of time it takes for an input to be registered and available to subsequent stages of the pipeline. Whereas First Input delay only measures the first interaction's input delay, not the time it takes to run event handlers or the delay in presenting the next frame.

Will Interaction to Next Paint (INP) Replace FID In Core Web Vital Reports?

Yes, INP will eventually replace FID as the Core Web Vitals metric. Google representatives pointed out that FID has some reasonably big blind spots. For example, First Input Delay (FID) only accounts for the first interaction. Moreover, it only measures input delay, not the processing time of event handlers or the delay in displaying the next frame. In contrast, INP considers all page interactions.

Given that FID is also a load responsiveness metric, its rationale is that if the first interaction made with a page in the loading phase has little to no perceptible input delay, the page has made a good first impression.

INP goes beyond first impressions. From the moment the page begins loading until the moment the user leaves, INP tracks the entire range of interactions that may occur.

This approach provides a comprehensive look at responsiveness and makes INP a more reliable indicator of responsiveness than FID.

It's best to think of INP as similar to Cumulative Layout Shift (CLS). It is a full-cycle metric that continually changes and updates throughout the entire lifecycle of the page. Like CLS, you do not want to record an INP value before the user leaves the page.

Optimize Web Pages for Interaction to Next Paint (INP)

Since Interaction to Next Paint (INP) is a new metric, webmasters and SEOs have to learn how to interpret this data. It will take a while for the industry to agree on an acceptable level of INP. Therefore, you must start measuring your website’s INP now and keep measuring it until the industry has some agreed-upon thresholds.

Keep in mind that Google doesn't expect you to reach zero or even near-zero values to get a good score. It is more important that the trend is positive and your website's performance is improving over time.

Here are some tips from Google to improve INP:

1. Identify all user interactions on your page (e.g., clicks, scrolls, form submissions, etc.) and measure the input delay for each one (see the section below for details).

2. Measure the input delay for each interaction on many different devices (desktop/laptop, mobile, tablet).

3. Measure over multiple days (preferably at least 5 days per week) using different devices and internet connections (e.g., home WiFi/cellular).

4. As soon as you obtain reliable data, work with your engineers/developers to improve input delay by optimizing event handlers or resolving network issues.

5. If you don't have access to engineers/developers who can help optimize your code or resolve network issues, try using AMP, which has been built from the ground up with performance in mind.

6. Measure again after making changes and iterate until your input delay is consistently fast.

If you use Google Analytics, here is a guide on measuring input delay in GA.

Continue to Optimize Interaction to Next Paint (INP)

It is highly recommended to measure the Interaction to Next Paint (INP) metric for your website because it is crucial for user experience and SEO. You can use it to evaluate your website against competitors and see how much time you need to decrease before you can claim that your website is “responsiveness optimized.”

It will help improve your SEO once it officially becomes a Core Web Vitals metric, but it is also just an excellent best-practice UX tactic that can improve other KPIs such as conversion rates.

Suppose you don’t have the resources or time to optimize your website right now. In that case, we suggest starting with the low-hanging fruits like lazy loading of images and videos, pre-caching content, and optimizing the critical rendering path (doing these steps will make a huge difference in responsiveness).

INP is one of the metrics to track page experience for users. Therefore, your website must be optimized for all the Core Web Vitals metrics to improve SERP rankings. Read our Core Web Vitals Guide to improve and automate your page experience optimization efforts.

About The Author

James Gibbons

James Gibbons is the Senior Customer Success Manager at Quattr. He has 9 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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