What Is INP (Interaction to Next Paint)? The Core Web Vital Explained

INP, short for Interaction to Next Paint, is the Core Web Vital that measures how fast your page responds to visitor interactions: a click, a tap or a keystroke. Since 12 March 2024, interaction to next paint has replaced the old First Input Delay (FID) metric as the official yardstick for responsiveness. Where FID only looked at the very first interaction, INP judges how smooth your site feels throughout the entire visit. In this article you will learn what INP measures exactly, which values are good and how to improve your INP for the long run.

What is INP exactly?

INP measures the time between the moment a visitor starts an interaction and the moment the browser paints the visible result on screen. Click a button, and INP counts how long it takes before you see something happen: a menu opening, a form responding, a price appearing.

According to Google’s web.dev, INP looks at every interaction during a visit, from the input delay through running the associated scripts to painting the next frame. INP then reports the slowest representative interaction. That makes the metric a far fairer reflection of how your site really feels than the old FID, which only measured the delay of the first interaction.

INP is one of the three Core Web Vitals. Together with LCP for loading speed and CLS for visual stability, it forms the set of measurable user experience signals Google takes into account. You can read the broader picture in our explainer on Core Web Vitals.

INP versus FID: what changed?

FID (First Input Delay) measured only the delay of the first interaction on a page, and even then just the part before the browser started processing. That painted a flattering picture: plenty of sites scored green on FID while feeling sluggish in practice on later clicks.

INP closes that gap. It officially became a Core Web Vital on 12 March 2024 and replaced FID right away. The differences at a glance:

• Scope. FID looked at one interaction, INP at every interaction during the visit.
• What it measures. FID measured only the input delay, INP measures the full path until the screen responds.
• Fairness. INP gives a more realistic picture of the responsiveness your visitor actually experiences.

If you still work with older documentation or tools that mention FID, read our separate explainer on what FID was to get the difference clear.

What is a good INP?

Google applies three clear thresholds, measured at the 75th percentile of your visits on mobile and desktop:

• Good: 200 milliseconds or less.
• Needs improvement: more than 200 and up to and including 500 milliseconds.
• Poor: more than 500 milliseconds.

That 200 millisecond threshold is not an arbitrary number. It is the boundary below which an interaction feels “instant” to most people. Go above it and your visitor notices a perceptible stutter, and that is exactly the kind of friction that makes people drop off.

How do you improve your INP?

The biggest culprit behind a poor INP is almost always heavy JavaScript hogging the browser’s main thread. As long as the browser is busy executing code, it cannot respond to your visitor’s click. So the gain lies in less and smarter work for that main thread:

• Break up long tasks. Large chunks of JavaScript that run in one go block interactions. Chop them into smaller pieces so the browser can respond in between.
• Defer non-essential scripts. Load whatever is not needed straight away later on, so the first interactions stay smooth.
• Limit third-party code. Trackers, chat widgets and external scripts are often the silent slowdown. Every piece you drop or defer creates breathing room.
• Optimise your event handlers. Heavy calculations on every click or scroll feed straight into your INP.

This is technical work that surfaces in a structured SEO audit, where we pull the loose threads together into a priority list. As an SEO specialist, we do not treat responsiveness as isolated technical candy, but as a building block of your conversion.

Honestly: how much does INP matter for B2B?

We would rather say it up front: do not chase a perfect INP score on a page nobody visits. A green checkmark is not a goal in itself. INP only really counts on the pages where your customers and your revenue are: your service pages, your strongest knowledge articles, your most important landing pages.

In B2B, a decision maker often goes through several steps before requesting a quote, and every slow response along the way increases the chance they drop out. A fast, responsive page keeps that decision maker engaged. But if you barely have any traffic yet, or your page already loads quickly, your energy is better spent on visitors and your offer than on chasing the last few milliseconds. Steer on leads and revenue, not on a dashboard full of green dots.

Frequently asked questions about INP

What does INP mean? INP stands for Interaction to Next Paint. It is the Core Web Vital that measures how fast your page responds to visitor interactions, from the click to the moment the screen shows the result.

When did INP replace the FID metric? On 12 March 2024, INP officially became a Core Web Vital and replaced FID right away. FID measured only the first interaction, INP looks at every interaction during the visit.

What is a good INP value? An INP of 200 milliseconds or less counts as good. Between 200 and 500 milliseconds needs improvement, and above 500 milliseconds the responsiveness is poor. Google measures this at the 75th percentile of your visits.

How do I improve my INP fastest? Usually by tackling heavy JavaScript: breaking up long tasks, deferring non-essential scripts and limiting third-party code. That gives the browser room to respond to interactions faster.

Does your site feel slow on click?

INP puts its finger on a pain point visitors feel but rarely name: a site that stutters on interaction. We find out which scripts are slowing your responsiveness down and tackle the pages where your customers come in, not every page blindly. We are a small team that moves fast and tells you honestly where the real gain is. Book your free intake