# 01 - INP: The New Critical Metric That Replaced FID

INP (Interaction to Next Paint) replaced FID as the Core Web Vitals responsiveness metric in March 2024. 43% of sites still fail the 200ms threshold. Learn how to measure it with Chrome DevTools and field data, and why it changes how we think about JavaScript architecture.

## What you'll learn

- Come INP differisce da FID e perche misura la responsivita reale
- Le soglie Good/Needs Improvement/Poor di INP (200ms / 500ms)
- Come misurare INP con Chrome DevTools, web-vitals.js e PageSpeed Insights
- I cinque pattern JavaScript piu comuni che fanno esplodere l'INP
- Come interpretare i dati di campo CrUX vs i dati sintetici Lighthouse

*This article is part of the **Core Web Vitals** series on federicocalo.dev.*

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## Read the full article

The complete article (9 min read) with code examples, diagrams, and practical exercises is available here:

**➡️ [01 - INP: The New Critical Metric That Replaced FID](https://federicocalo.dev/en/blog/inp-interaction-to-next-paint-complete-guide)**

`https://federicocalo.dev/en/blog/inp-interaction-to-next-paint-complete-guide`

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*By [Federico Calò](https://federicocalo.dev) — Software Developer & Technical Writer*