Glossary · SEO & AI searchTOFU
INP (Interaction to Next Paint)
The short answer
INP (Interaction to Next Paint) measures how quickly a page responds visually after a user interacts with it — a tap, a click or a key press — across the whole visit. It replaced First Input Delay as a Core Web Vital in 2024.
Good INP is 200 milliseconds or less. Above that, pages start to feel sluggish; above 500 milliseconds they feel broken.
What causes poor INP
- Large JavaScript bundles running on the main thread
- Third-party scripts — chat widgets, heatmaps, multiple pixels
- Expensive re-renders in JavaScript frameworks
- Heavy work triggered on every tap or keystroke
Fixes
- Ship less JavaScript and split it by route
- Defer or remove non-essential third-party scripts
- Move tracking server-side where possible
- Break long tasks into smaller chunks
- Test on mid-range Android devices, not just laptops
INP thresholds
| Rating | INP |
|---|---|
| Good | ≤ 200 ms |
| Needs improvement | 200–500 ms |
| Poor | > 500 ms |
Source: web.dev. INP replaced First Input Delay as a Core Web Vital in March 2024. See Core Web Vitals.
INP in practice
A product page with heavy scripts responds slowly when users tap "add to cart". Reducing JavaScript and optimising event handlers improves INP and the shopping experience.
How to improve INP
- Reduce heavy JavaScript
- Break up long tasks
- Optimise third-party scripts
Common INP mistakes
- Heavy third-party scripts
- Long JavaScript tasks on interaction
- Testing only on fast devices
Frequently asked questions
Why is INP worse on mobile?
Mobile processors are slower, so the same JavaScript takes longer to run.
Does INP affect conversions?
Yes — unresponsive buttons and forms frustrate users at exactly the moments that matter.
How do I find what causes poor INP?
Use Chrome DevTools performance profiling and real-user monitoring to find slow interactions and long tasks.
Do pop-ups and chat widgets affect INP?
They can, if they run heavy scripts. Load them efficiently and only where needed.
What replaced FID?
INP replaced First Input Delay as a Core Web Vital in 2024.
What's a good INP?
200 milliseconds or less is considered good.
Related terms
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