Interaction to Next Paint (INP) replaced First Input Delay (FID) as a Core Web Vital in March 2024. FID only measured the wait before the first interaction began processing. INP looks at every click, tap and key press during a visit and reports roughly the slowest one, so it reflects responsiveness more completely.
Why it matters
Old articles, tools and audit reports still mention FID. If you follow advice that targets FID, you may fix the wrong thing. A page can have an excellent FID and still feel sluggish because the first tap was fast while later ones were not.
The two metrics differ in three ways:
- Scope: FID looked at the first interaction only. INP covers all interactions in the visit.
- What is timed: FID measured only input delay, the gap before event handlers start. INP measures the full path: input delay, handler processing and the time to draw the next frame.
- Threshold: FID was considered good at 100 milliseconds or less. INP is good at 200 milliseconds or less.
How to check what applies to you
- Open PageSpeed Insights for your page and read the field data block. It should list LCP, INP and CLS, not FID.
- In Search Console, open the Core Web Vitals report. It groups URLs by LCP, INP and CLS status.
- If a monitoring tool or dashboard still shows FID, check whether it has an INP option and switch to it.
- Treat any FID chart as historical. It no longer counts toward the Core Web Vitals assessment.
The current set and its good thresholds, measured at the 75th percentile of page loads:
| Metric | Measures | Good |
|---|---|---|
| LCP | Loading | 2.5 s or less |
| INP | Responsiveness | 200 ms or less |
| CLS | Visual stability | 0.1 or less |
Common mistakes
- Optimising for FID targets from older checklists.
- Assuming a low FID means INP will also be good.
- Testing only the first click and ignoring menus, filters and form fields used later in the visit.
- Reading Total Blocking Time in Lighthouse as if it were INP. It is a lab signal related to main-thread work, not the same measurement.
Frequently asked questions
Is FID still measured anywhere?
Some older tools and historical datasets may still show it, but it is no longer part of the Core Web Vitals set. Use INP when judging responsiveness.
Do I need to redo my FID fixes?
Not necessarily. Reducing long JavaScript tasks helps both metrics. But recheck with INP, because slow event handlers or rendering can hurt INP even when FID looked fine.
When did the change happen?
INP became a stable Core Web Vital in March 2024, replacing FID. Google's web.dev documentation describes the change and the reasons behind it.
Related guides
- Improve Interaction to Next Paint
- Core Web Vitals explained
- Core Web Vitals report in Search Console
- Reduce JavaScript bundle size
Curious how your site responds today? Try the free website sample.