---
title: "What is Interaction to Next Paint (INP)? · Unlighthouse"
meta:
  "og:description": "INP measures responsiveness. Learn what it is, thresholds, and how to improve interaction speed."
  "og:title": "What is Interaction to Next Paint (INP)? · Unlighthouse"
  description: "INP measures responsiveness. Learn what it is, thresholds, and how to improve interaction speed."
---

**Glossary**

# **What is Interaction to Next Paint (INP)?**

[Copy for LLMs](https://unlighthouse.dev/glossary/inp.md)

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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 now a Google ranking factor.

## [Thresholds](#thresholds)

| **Score** | **Rating** |
| --- | --- |
| ≤ 200ms | Good |
| 200ms - 500ms | Needs Improvement |
| > 500ms | Poor |

[**Google recommends**](https://web.dev/articles/inp) 200 milliseconds or less for at least 75% of page visits.

## [INP vs FID](#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](#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](#common-issues)

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

## [Measure INP](#measure-inp)

- [**Core Web Vitals Checker**](https://unlighthouse.dev/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**](https://unlighthouse.dev/glossary/tbt) as lab proxy

→ [**Complete INP Guide**](https://unlighthouse.dev/learn-lighthouse/inp)

[Edit this page](https://github.com/harlan-zw/unlighthouse/edit/main/docs/glossary/inp.md)

[Markdown For LLMs](https://unlighthouse.dev/glossary/inp.md)

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[**FCP** FCP measures when the first content renders. Learn what it is, thresholds, and how to improve it.](https://unlighthouse.dev/glossary/fcp) [**LCP** LCP measures loading performance. Learn what it is, thresholds, and how to improve your score.](https://unlighthouse.dev/glossary/lcp)

**On this page **

- [Thresholds](#thresholds)
- [INP vs FID](#inp-vs-fid)
- [Why It Matters](#why-it-matters)
- [Common Issues](#common-issues)
- [Measure INP](#measure-inp)