INP replaces FID as a Core Web Vital on March 12

On March 12, Interaction to Next Paint (INP) will officially become a Core Web Vital, taking over the responsiveness role from First Input Delay (FID), which will be deprecated. The Chrome team first introduced INP as an experimental metric in May 2022, recognizing that FID did not fully capture interactivity on the web. INP was later promoted to a pending metric before the announcement that it would reach stable status in March 2024.

INP measures latency for all interactions on a page, not just the first one as FID does, providing a more holistic view of responsiveness. Core Web Vitals are evaluated based on field data at the 75th percentile of all page loads.

How to assess your current INP

The quickest way to check whether your site meets the "good" INP threshold is through PageSpeed Insights, which pulls data from the Chrome User Experience Report (CrUX) — the official dataset of the Web Vitals program. If you use a Real User Monitoring (RUM) provider, ask whether they support INP reporting.

For sites where INP falls into the "needs improvement" or "poor" categories, several resources are available for diagnosing and troubleshooting slow interactions:

  • Find slow interactions in the field using field data analysis techniques
  • Manually diagnose slow interactions in the lab

Once you've identified problem areas, the following guides cover common optimization targets:

  • Optimize long tasks — especially if script evaluation during page load is creating excessive main thread activity
  • Optimize input delay when there's a long gap between an interaction occurring and processing beginning
  • The rendering work that follows interaction-driven DOM changes can be minimized by avoiding large, complex layouts and layout thrashing
  • Minimize DOM size where possible, since large DOMs require significant rendering when changed
  • Simplify complex CSS selectors, which can cause substantial work in response to interactions
  • Understand how client-side rendering of HTML affects interactivity, particularly for sites that render much of their HTML via JavaScript

Optimizing INP has proven business value. Case studies from The Economic Times and redBus demonstrate that reducing interaction latency correlates with improved business outcomes.

What changes on March 12

When INP becomes a Core Web Vital, FID will cease to be one and will be officially deprecated. FID documentation will remain available but will carry prominent notices about its deprecated status with redirects to relevant INP documentation where appropriate.

The transition timeline varies by tool:

  • Google Search Console will remove FID immediately on March 12
  • Other tools, including PageSpeed Insights and CrUX, will maintain FID support during a six-month deprecation period so developers can update their code

For questions about INP's effect on Google Search, refer to the announcement previously published on Google Search Central. The Chrome team also invites feedback on INP, FID, or any other Web Vitals metrics at [email protected].

The promotion of INP to a stable Core Web Vital marks the culmination of two years of planning. Its more comprehensive approach to measuring responsiveness gives developers a better baseline for assessing and improving interaction latency, with the expectation of a more responsive web across the industry as a result.