What is INP?

INP (Interaction to Next Paint) measures how quickly a page responds to interactions. It looks at the clicks, taps and keyboard interactions during a visit and reports a value close to the slowest. It replaced FID as a Core Web Vital in March 2024. FID only measured the input delay of the first interaction; INP covers every interaction, up to the moment the screen updates.

#Why it matters

• Tapping "Add to cart" and seeing nothing for half a second feels broken and leads to repeated taps.
• The most common cause of high INP is heavy JavaScript that keeps the main thread busy: large bundles, third-party tags, long tasks.

#Where you see it in SEOAsist

• On the Core Web Vitals card on the Overview page the row is labelled INP / TBT. INP needs a real interaction, so lab measurements don't always produce it; in that case PageSpeed's TBT (Total Blocking Time) is shown. TBT is a good lab proxy for INP.
• SEO analysis raises a High interaction delay finding when the value exceeds 200 ms.

More: Overview dashboard.

#Example

Split long work so the browser gets a chance to paint first:

button.addEventListener("click", async () => {
  showSpinner();                                  // visual feedback first
  await new Promise((r) => setTimeout(r, 0));     // yield the main thread
  recalculateCart();                              // heavy work afterwards
});

#Common mistakes

• Loading every analytics and chat widget on page load; defer them or load on interaction.
• Testing only on desktop; INP is much worse on low-powered phones.
• Still looking at FID; Google no longer reports it.