What it means
INP looks at the interactions during a visit and reports one of the slowest: the time from the input to the next frame drawn. It replaced First Input Delay as a Core Web Vital in March 2024.
web.dev defines a good INP as 200 milliseconds or less and a poor one as more than 500 milliseconds, at the 75th percentile. Lab tests can’t measure INP without real interactions, so they use Total Blocking Time (TBT) as a stand-in.
Why it matters
When the main thread is busy running JavaScript, the page can’t react: buttons seem dead, menus open late, and people tap again. Long tasks from large scripts, tag managers and third-party widgets are the usual cause.
Google uses Core Web Vitals, including INP, in its ranking systems.
How to find it yourself
- PageSpeed Insights shows field INP when your site has enough Chrome traffic.
- In Chrome DevTools, the Performance panel shows long tasks and which scripts they come from.
How to fix it
On any website
- Remove scripts you don’t need and delay the rest until after the page is usable (defer, or load on interaction).
- Break up long tasks so the browser can respond between them, and keep event handlers short.
- Audit third-party tags: chat widgets, A/B testing and tracking scripts often cause the longest tasks.
On Shopify
- Uninstall unused apps and check that their code was removed from the theme; switch off unused app embeds in the theme editor.
On WordPress and WooCommerce
- Deactivate plugins that load scripts on every page, and use a plugin or theme setting to delay non-essential JavaScript.
How to check the fix
- Run the speed test for TBT right away; field INP changes over the following 28 days.
How FixReports finds it
The speed test reports field INP from the Chrome UX Report when available, and measures Total Blocking Time in a throttled phone load. We flag a TBT over 200 ms.