What are Core Web Vitals (LCP, FID, CLS, INP) in 2024

Written by Priyanka Kumari | Mar 25, 2024
What are Core Web Vitals (LCP, FID, CLS, INP) in 2024

Ever feel frustrated waiting for a web page to load? Core Web Vitals (CWV) are a set of metrics designed to address this issue, focusing on real-world user experience. Let’s delve into these metrics, LCP, FID and CLS to understand how to optimize them, and decipher the parameters that define good, needs improvement, and poor performance.

What are Core Web Vitals

Core Web Vitals are a set of three essential metrics established by Google to measure real-world user experience for loading speed, interactivity, and visual stability of a web page. They represent a critical aspect of Google’s “page experience” score, which significantly impacts search engine ranking.

Optimizing for Core Web Vitals benefits both users and website owners by ensuring a smooth and frustration-free browsing experience. Utilize tools like Google’s PageSpeed Insights tool identifies areas for improvement, like optimizing images and minifying code.

Core Web Vitals Metrics:

Largest Contentful Paint (LCP)

This metric measures how long it takes for the largest content element on your page to load. Imagine a newspaper; LCP is when the main headline is fully visible.

LCP Largest Contentful Paint

Example: A large product image on an e-commerce page.
Optimization Tips: Reduce image sizes, leverage browser caching, minimize render-blocking JavaScript.

Interaction Network Response (INP)

INP, or Interaction to Next Paint, is an upcoming Core Web Vital metric that has replaced FID (First Input Delay) in March 2024. Interaction to Next Paint (INP) is a stable Core Web Vital metric that check how responsive a webpage is by looking at how long it takes for the page to show something (like a change of color) after you click, tap, or type something.

Interaction to Next paint

INP considers all these actions throughout your visit and picks the slowest one, ignoring any super quick or slow outliers. A website with a low INP generally feels fast and responsive because it reacts quickly to most things you do on it.

Cumulative Layout Shift (CLS)

CLS measures visual stability. It calculates the sum of layout shifts of unexpected content movement on your page during loading. Think of it as elements jumping around as the page loads, disrupting the user’s experience.

Cumulative layout Shift (CLS)
Example: Ads or images appearing and pushing other content down the page.
Optimization Tips: Set dimensions for images and videos beforehand, avoid lazy loading above the fold content, use CSS containment for specific elements.

First Input Delay (FID)

FID measures the responsiveness of your page. It’s the time between a user interacting with your page (clicking a button) and the browser acknowledging the interaction. Essentially, it reflects how fast your page feels.

First Input Delay

Example: Clicking a “Buy Now” button and waiting for it to react.
Optimization Tips: Minimize JavaScript execution time, prioritize critical rendering tasks, reduce unnecessary DOM manipulation.

Additional Core Web Vitals Metrics to Consider

While not part of the core set, these additional metrics provide valuable insights into website performance:

First Contentful Paint (FCP): Tracks how long it takes for the first content element (text, image, etc.) to render on the page.
Total Blocking Time (TBT): Measures the total time the browser is blocked from rendering content due to JavaScript execution.

How INP (Interaction to Next Paint) Works?

  • User interacts with the page (clicks a button, types in a form, etc.)
  • The browser receives the interaction event.
  • The browser processes any network events related to the interaction.
  • The browser paints the next frame, visually acknowledging the user interaction.
  • INP measures the duration of step 3. It focuses on the longest interaction delay a user experiences
  • during their visit, providing a more user-centric perspective on responsiveness compared to FID.

Optimizing for INP

Techniques that improve FID will generally benefit INP as well. Here are some additional tips:

  • Minimize JavaScript execution time.
  • Prioritize critical rendering tasks.
  • Reduce unnecessary DOM manipulation.
  • Leverage techniques like requestIdleCallback for non-critical tasks.


By focusing on Core Web Vitals and optimizing for INP, you can create a website that feels fast and responsive to users, leading to a more positive browsing experience and potentially improving your search engine ranking. It’s does not directly affect your ranking but It is a also major google ranking factors which consider by Google.


What are the 3 pillars of Core Web Vitals?

Core Web Vitals are essential part of SEO that measure real-world user experience on the web. The 3 pillers are: Largest Contentful Paint (LCP), Interaction to Next Paint (INP) replacing FID (First Input Delay), and Cumulative Layout Shift (CLS).

What is the most important Core Web Vital?

While focusing on all three metrics is essential and Important but, LCP considered the most foundational metric. If your website takes too long to load the main content (high LCP), users might leave before even experiencing INP or CLS.

Is Core Web Vitals technical seo?

Core Web Vitals (CWV) straddle the line between technical SEO and user experience (UX) optimization. While they are directly related to SEO, they focus more on the user’s experience on your website. Optimizing Core Web Vitals often involves technical solutions like image compression, code minification, and efficient server-side rendering. These fall under the umbrella of technical SEO.