Glossary
What is Interaction to Next Paint (INP)?
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Interaction to Next Paint (INP) measures how quickly your page responds to user interactions. It replaced FID as a Core Web Vital in March 2024 and is now a Google ranking factor.
Thresholds
| Score | Rating |
|---|---|
| ≤ 200ms | Good |
| 200ms - 500ms | Needs Improvement |
| > 500ms | Poor |
Google recommends 200 milliseconds or less for at least 75% of page visits.
INP vs FID
FID only measured the first interaction's input delay. INP measures all interactions throughout the page lifecycle, including processing time and rendering. Since 90% of user time is spent after page load, INP better reflects actual experience.
Why It Matters
While 93% of sites had good FID, only 74% have good INP. Users expect instant feedback - slow interactions make sites feel broken.
Common Issues
- Long-running JavaScript blocking main thread
- Heavy event handlers
- Third-party scripts (analytics, ads)
- Hydration delays in SPAs
Measure INP
- Core Web Vitals Checker - test any page
- PageSpeed Insights (field data)
- Search Console Core Web Vitals report
- Web Vitals Chrome extension
- TBT as lab proxy
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