INP (Interaction to Next Paint)
INP measures how quickly a page responds visually to user input. Learn the thresholds, why it replaced FID, and how to improve a failing score.
TL;DR
INP measures how quickly a page responds visually after someone interacts with it. The clock starts when a user clicks, taps or presses a key, and stops when the next frame renders showing the result. It replaced First Input Delay as a Core Web Vital in March 2024, because FID measured only the wait before the first interaction and ignored everything afterwards.
Why INP matters
Responsiveness is the part of performance users feel most directly. A page that loads quickly and then freezes when clicked feels broken regardless of its load time.
- Whole-session coverage: INP considers all interactions on a page, not just the first one.
- Perceived speed: Users judge a page by whether it reacts, which correlates far better with INP than with load metrics.
- Ranking signal: As a Core Web Vital it feeds page experience signals, modestly.
- Interaction quality: Forms, filters and menus are where conversions happen, and those are exactly what INP measures.
How to improve INP
Break up long tasks
Any script blocking the main thread beyond about 50 milliseconds delays every interaction. Split work into smaller chunks.
Defer non-critical JavaScript
Analytics, chat widgets and personalisation scripts rarely need to run before the page becomes interactive.
Yield to the main thread
Let the browser render between chunks of work instead of holding the thread through a long operation.
Reduce event handler work
Handlers doing heavy computation on every click or keystroke delay the visual response directly.
Simplify the DOM
Very large or deeply nested DOM trees make every style recalculation and repaint more expensive.
Audit third-party scripts
Tag managers and embedded widgets are a frequent cause, and they are often the easiest thing to remove.
INP vs. First Input Delay
INP: Measures every interaction across the page visit and reports close to the worst. Covers the full input-to-paint cycle, including processing and rendering.
First Input Delay: Measured only the delay before the first interaction began processing. It ignored how long the work took and everything after.
FID was generous by design, and most pages passed it while still feeling sluggish. INP is stricter and more honest, which is why many sites saw scores drop when the switch happened without anything on the page changing.
Performance sits alongside crawlability and structure in whether pages get used by engines at all. Findrix runs a 31-point technical audit covering rendering and crawler access, then tracks how often seven AI engines cite you against named competitors. Every gap comes with the fix already written: technical, content and off-site. The audit is free, takes about a minute, and requires no signup.
INP thresholds and measurement
- Good: 200 milliseconds or less.
- Needs improvement: Between 200 and 500 milliseconds.
- Poor: Above 500 milliseconds.
- Assessment point: The 75th percentile of visits, so most users must have a good experience.
- Field data: Real Chrome usage decides the score; lab tools help diagnose but do not set it.
- What counts: Clicks, taps and key presses. Scrolling and hovering are excluded.
Why scores dropped when INP arrived
A lot of teams watched a passing metric turn into a failing one in March 2024 without shipping a single change, and reasonably concluded the measurement was unfair.
It was not unfair; it was more complete. FID stopped its clock the moment processing began, which meant a page could start handling a click promptly, spend 800 milliseconds computing, and still record an excellent score.
The work is nearly always JavaScript execution rather than images or fonts. Start with third-party scripts, which cause a disproportionate share and are least defended.
Frequently asked questions
What is a good INP score?
200 milliseconds or less at the 75th percentile of real visits. Between 200 and 500 needs improvement, and above 500 is poor.
Why did INP replace First Input Delay?
FID measured only the delay before the first interaction started processing, which most pages passed easily while still feeling slow. INP measures every interaction through to the visual response, which reflects the actual experience.
How do I measure INP?
Search Console and the Chrome User Experience Report provide field data from real visits. Lighthouse and DevTools help identify which scripts and handlers cause delays, but lab tools cannot produce the official score.