---
title: "INP (Interaction to Next Paint)"
slug: "inp"
category: "glossary"
tags: ["glossary", "seo", "performance", "core-web-vitals", "inp"]
status: "stable"
last_updated: 2026-05-14
summary: "INP (Interaction to Next Paint) is the Core Web Vital measuring worst interaction latency; the good threshold is under 200 ms at the 75th percentile."
related:
  [
    "[[glossary/core-web-vitals]]",
    "[[seo/core-web-vitals]]",
    "[[glossary/lcp]]",
    "[[glossary/cls]]",
    "[[seo/page-speed]]",
    "[[frontend/react-performance]]",
  ]
---

## Overview

This page is the atomic definition. The deep-dive lives at [[seo/core-web-vitals]].

## Definition

INP (Interaction to Next Paint) is the Core Web Vital that measures responsiveness across every click, tap, and key press on a page. It reports the longest interaction latency at the 75th percentile of real users over a 28-day field window. The "good" threshold is under 200 milliseconds; "needs improvement" is 200 to 500 ms; "poor" is 500 ms or more. INP replaced First Input Delay (FID) in March 2024.

## When it applies

Use INP as the responsiveness budget for any interactive page. It surfaces long JavaScript tasks, hydration cost, and third-party script blocking that single-interaction metrics miss.

## Example

A React app hydrates the full page on load and ships INP 420 ms. Splitting into Astro islands and gating analytics behind interaction drops INP to 160 ms.

## Related concepts

- [[glossary/core-web-vitals]] - the umbrella metric set INP belongs to.
- [[frontend/react-performance]] - hydration and long-task patterns that move INP.
- [[seo/page-speed]] - the broader speed picture, including TTFB and FCP.
- [[glossary/lcp]] - the loading metric, scored on a separate budget.
- [[glossary/cls]] - the layout-stability metric, scored on a separate budget.

## Citing this term

> See [[glossary/inp|INP (Interaction to Next Paint)]] (llmbestpractices.com/glossary/inp).

## Related

- [[seo/core-web-vitals]]
- [[seo/page-speed]]
- [[frontend/react-performance]]
- [[glossary/core-web-vitals]]
- [[glossary/lcp]]