Interaction to Next Paint (INP) rolled out

What does this mean for Core Web Vitals? And how will this impact your website?

Two years after the successful launch of the Core Web Vitals in early 2020, Google announced they would be launching a new metric known as Interaction to Next Paint (INP). The original core web vitals did not take into account the engagements made on a page after it loads, and therefore INP was introduced to bridge this gap.

Today (March 12th 2024), INP has officially replaced the previous metric known as First Input Delay (FID).

What does Interaction to Next Paint (INP) measure?

INP measures the speed at which a website responds to user interactions, throughout their time spent on the page. Interactions measured by INP include clicks, taps, and keyboard presses – but other interactions such as hovering, or scrolling are not included.

For pages with fewer than 50 interactions, INP is assessed for the interaction that has the most latency – and for those with more than 50 interactions, it measures the 98th percentile of interaction latency.

For a seamless user experience, pages should respond quickly to interactions; the speed at which visual feedback is provided to these interactions, represented by the next frame presented after a click for example, impacts the user experience. Slow response time may give users the impression that the page is not responding to their actions, and is lagging or delayed – resulting in a bad user experience.

There are occasions where an INP score might not be available for a webpage, for example if:

• The webpage was loaded, but the user did not engage with any of the interactive elements of the webpage
• The user interacted with the page by hovering over elements or scrolling down the page – both interactions not included in the INP score
• The page was accessed by a bot

If this is the case, then the best alternative metric to check would be Total Blocking Time (TBT). TBT measures how long the page is blocked from responding to interactions while it is loading.

How does INP differ from First Input Delay (FID)?

While First Input Delay (FID) only considers the first interaction following the page load, INP takes into account not only the first interaction but all subsequent interactions with a page during the entire duration of user engagement.

FID was limited by failing to detect poor user experience beyond the first interaction; INP aims to remedy this by providing a comprehensive analysis of page responsiveness, providing a better gauge of user satisfaction.

What qualifies as ‘good’ INP?

An INP score below 200 milliseconds signals that your page has ‘good responsiveness. Any score above 200 milliseconds, but below 500 milliseconds means that your responsiveness needs improvement. An INP score above 500 milliseconds indicated poor responsiveness.

How can INP be improved?

Reducing the amount of CPU processing on your page is the most effective way to improve your INP score; there are several ways in which this can be achieved:

Javascript

Reducing the size of JavaScript files will help them load faster. You can use a JavaScript framework tool to help organise your code to increase efficiency. Minimising, or breaking up long JavaScript tasks into smaller, more manageable chunks frees up the CPU to perform more essential tasks.

Minimise file sizes

In a similar fashion to the above, minimising file size of other page elements – such as images and scripts will also increase efficiency of the CPU.

Use a Content Delivery Network (CDN)

By using a Content Delivery Network (CDN), your JavaScript files will be loaded from servers close to your user, which will improve load speed.

Benefits of improving my INP

Only 64% of websites are currency performing well on the INP metric

Considering that your website scores on the Core Web Vitals have an impact on your organic search ranking, it is likely that there will be a strong correlation between website ranking and INP.

The Economic Times discovered that by improving their INP score they have seen additional business benefits, such as reducing their bounce rate by 50%. This means that people visiting their website are twice as likely to remain on the site and further explore their content.

Improving your INP score will ultimately increase website speed, improve user experience, and boost organic search performance.

Summary & final remarks

Google’s recent launch of Interaction to Next Paint (INP) marks a significant development in web performance metrics, replacing the previous First Input Delay (FID) metric. INP aims to provide a more comprehensive understanding of user experience by evaluating all interactions with a web page, not just the initial one.

With substantial benefits including enhanced user experience, increased website speed, and improved organic search performance, the INP metric has become crucial for website owners.