---
title: "What is interaction to next paint (INP)?"
description: "INP measures responsiveness. Learn what it is, thresholds, and how to improve interaction speed."
canonical_url: "https://unlighthouse.dev/glossary/inp"
last_updated: "2026-08-10T04:33:19.096Z"
---

<interactive-inp-lab>



</interactive-inp-lab>

Interaction to Next Paint (INP) measures how quickly your page responds to user interactions. It [replaced FID as a Core Web Vital](https://web.dev/blog/inp-cwv-march-12) in March 2024 and is a Google ranking factor.

## Thresholds

<table>
<thead>
  <tr>
    <th>
      Score
    </th>
    
    <th>
      Rating
    </th>
  </tr>
</thead>

<tbody>
  <tr>
    <td>
      ≤ 200ms
    </td>
    
    <td>
      Good
    </td>
  </tr>
  
  <tr>
    <td>
      200ms - 500ms
    </td>
    
    <td>
      Needs Improvement
    </td>
  </tr>
  
  <tr>
    <td>
      > 500ms
    </td>
    
    <td>
      Poor
    </td>
  </tr>
</tbody>
</table>

Aim for a score of 200 milliseconds or less at the 75th percentile of page loads to pass the [Google threshold](https://web.dev/articles/inp).

## INP vs FID

FID only measured the first interaction's input delay. INP measures all interactions throughout the page lifecycle, including processing time and rendering. Since [90% of user time is spent after page load](https://web.dev/articles/inp), INP better reflects actual experience.

## Why it matters

While [93% of sites had good FID](https://web.dev/blog/inp-cwv), only [74% have good INP](https://almanac.httparchive.org/en/2024/performance). Users expect instant feedback - slow interactions make sites feel broken.

## Common issues

- Long-running JavaScript blocking main thread
- Heavy event handlers
- Third-party scripts (analytics, ads)
- Hydration delays in SPAs

## Measure INP

- [Core Web Vitals Checker](/tools/cwv-checker) - test any page
- [PageSpeed Insights](https://pagespeed.web.dev/) (field data)
- Search Console Core Web Vitals report
- Web Vitals Chrome extension
- [TBT](/glossary/tbt) as lab proxy

→ [Complete INP guide](/learn-lighthouse/inp)