---
title: "What is interaction to next paint (INP)? · Unlighthouse"
canonical_url: "https://unlighthouse.dev/glossary/inp"
last_updated: "2026-08-18T03:20:27.756Z"
meta:
  description: "INP measures responsiveness. Learn what it is, thresholds, and how to improve interaction speed."
  "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"
---

Star Unlighthouse on GitHubUnlighthouse on GitHub

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[**API **](https://unlighthouse.dev/api-doc/config)

**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 a Google ranking factor.

## Thresholds

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

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~~**](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/inp.md)

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

**Did this page help you? **

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Help us improve this page. You can [~~edit this page ~~](https://github.com/harlan-zw/unlighthouse/edit/main/docs/inp.md) on GitHub or provide anonymous feedback below.

### **Related **

[**INP Guide**](https://unlighthouse.dev/learn-lighthouse/inp) [**Core Web Vitals Checker**](https://unlighthouse.dev/tools/cwv-checker) [**Largest Contentful Paint (LCP)**](https://unlighthouse.dev/glossary/lcp) [**Cumulative Layout Shift (CLS)**](https://unlighthouse.dev/glossary/cls)

[**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)