INP Readiness

1. What Is INP Readiness?

INP Readiness indicates whether a web page’s Interaction to Next Paint (INP) — the delay between a user input (click, tap, key press) and the next visual change — stays below Google’s 200 ms threshold. If a page is “ready,” most interactions feel instantaneous, telling Google that the site reacts quickly to user intent.

2. Why It Matters for SEO

Google’s Core Web Vitals influence rankings. INP becomes a Core Web Vital in March 2024, replacing First Input Delay (FID). Pages that meet the 200 ms target gain two advantages:

• Higher likelihood of top-10 positions — fast, responsive sites reduce bounce rates and earn Google’s performance boost.
• Better user signals — low INP correlates with longer sessions and higher conversion, reinforcing positive engagement metrics Google monitors.

3. How INP Is Measured (Beginner Friendly)

• When a user interacts, the browser logs the time of the event (e.g., mousedown).
• It then waits for the next paint cycle — the moment a visible change appears on screen.
• The gap between these two timestamps is the INP for that interaction.
• During a session, Chrome collects all interactions and keeps the longest value. That “worst-case” number is what the CrUX report and PageSpeed Insights show.

4. Best Practices & Implementation Tips

• Minimize main-thread work: break long JavaScript tasks into smaller chunks with requestIdleCallback or setTimeout.
• Use passive event listeners: addEventListener('touchstart', handler, {passive: true}) keeps scrolling smooth.
• Defer non-critical scripts: load analytics and chat widgets after load or via async/defer.
• Avoid layout thrashing: batch DOM reads and writes. Tools like ResizeObserver help you detect costly reflows.
• Audit with Lighthouse and Web Vitals Chrome Extension to spot callbacks exceeding 50 ms.

5. Real-World Examples

• E-commerce product page: Replacing a jQuery carousel with a lightweight CSS slider cut INP from 350 ms to 110 ms, lifting add-to-cart clicks by 8%.
• News site: Moving social-share buttons to lazy-loaded iframes prevented a 180 ms JavaScript block, pushing INP under the 200 ms line.

6. Common Use Cases

• Checkout flows: Users abandon carts when form inputs lag. INP monitoring spots bottlenecks early.
• SaaS dashboards: Frequent button clicks and filter changes make responsiveness critical for perceived quality.
• Mobile landing pages: On slower devices, trimming INP is often the quickest win for Core Web Vitals compliance.