Core Web Vitals

Here we explain what Core Web Vitals are and why it is important that you are aware of Core Web Vitals.
Core web vitals

What are Core Web Vitals?

Core Web Vitals is a set of parameters that Google uses to measure user experiences on the Internet. There is no doubt that speed is an important part of Core Web Vitals, but there are many other important factors as well. Core Web Vitals is a set of user experience-focused metrics related to speed, responsiveness and visual stability. Speed ​​plays a big role in Core Web Vitals. Test the speed of your website here.

These Web Vitals are divided into two different categories: Core Web Vitals and Non-Core Web Vitals.

There are three subcategories for Core Web Vitals:

  • LCP- Largest Contentful Paint
  • FID – First Input Delay
  • CLS – Cumulative Layout Shift

There are four subcategories for Non-Core Web Vitals:

  • TBT – Total Blocking Time
  • FCP – First Contentful Paint
  • SI – Speed Index
  • TTI – Time to Interactive

Each category is a measurement unit that measures how good a part of your visitors’ Page Experience is. 

Before we delve into these different elements of Core Web Vitals, let’s delve into why Core Web Vitals are so important.

Why are Core Web Vitals important?

There are many different reasons why you should focus on Core Web Vitals. Here are three of the primary reasons:

  1. Users on the web love websites that are fast and provide a good user experience. If you focus on Core Web Vitals and create a good user experience, it will result in increased revenue, lower bounce rate and more conversions.
  2. Following Google’s latest algorithm updates, Core Web Vitals has become an important ranking factor. By focusing on Core Web Vitals, you therefore increase your probability of achieving good rankings on Google and thus get more organic traffic.
  3. By focusing on Core Web Vitals, you will, as previously described, give your visitors a better user experience. All other things being equal, this will result in lower bounce rates and higher conversion rates.

In-depth Core Web Vitals Guide

Let’s delve into the various sub-categories of Core Web Vitals.

Largest Contentful Paint (LCP)

Largest Contentful Paint measures how long in seconds it takes from a page starting to load until the largest text box or image is loaded on the screen.

The purpose of this measurement unit is to measure when a page’s content has been completely loaded. The lower an LCP you have, the better, as it means that your website is fast. LCP is important as it shows the perceived load time of the visitor.

What is a good LCP score?

Here is a general rule of thumb for understanding your LCP score:

  • Good: 2.5 seconds or less
  • Mediocre: Between 2.5 and 4 seconds
  • Bad: More than 4 seconds

First Input Delay (FID)

First Input Delay is a Core Web Vitals measurement unit that measures how many milliseconds it takes from a visitor to your website to press a link, button or other until your website can respond to this action. 

This measurement unit is therefore good for measuring your website’s interactivity and responsiveness. It is of course best to have as low an FID as possible.

What is a good FID score?

Here is a general rule of thumb for understanding your FID score:

  • God: Under 100ms
  • Mediocre: Between 100ms and 300ms
  • Bad: More than 300ms

Cumulative Layout Shift (CLS)

Cumulative Layout Shift is a Core Web Vital that measures the cumulative score of all the unexpected changes in layout that occur during a page’s entire life cycle.

The goal of this measurement unit is to measure a page’s visual stability. The visual stability has a big effect on the site’s user experience. The lower the CLS score the page has, the better.

This metric is not measured in seconds, but measures the movement of elements in the page’s viewport. This layout change score is the product of two different elements: Impact fraction and distance faction. 

What is a good CLS score?

The CLS score is therefore a bit more technical than the above, but here is a general rule of thumb for how you can understand your CLS score:

  • Good: Below o,1
  • Mediocre: Between 0.2 and 0.25
  • Poor: Above 0.25

Total Blocking Time (TBT)

Total Blocking Time is a Non-Core Web Vital score that measures how many milliseconds there are between FCP to TTI until the primary thread is blocked long enough to make it unresponsive to user input.

TBT is closely related to FID and is a good alternative to FID in a test environment when real user data is not possible. You can collect TBT data from real data, but it is influenced by user interactions and is therefore not a reliable unit to measure against. Therefore, TBT is only used in a test environment.

What is a good TBT score?

Here is a general rule of thumb for understanding your TBT score:

  • God: Under 200ms
  • Mediocre: Between 200ms and 600ms
  • Bad: Over 600ms

First Contentful Paint (FCP)

First Contentful Paint is a Non-Core Web Vital which measures how long it takes from the time a page starts to load to when any part of the website is loaded on the screen. It is good to have a fast FCP as it tells the visitor that the website is loading. 

What is a good FCP score?

Here is a general rule of thumb for understanding your FCP score:

  • Good: Under 1.8 seconds
  • Mediocre: Between 1.8 and 3 seconds
  • Bad: Over 3 seconds

Speed Index (SI)

Speed ​​Index is a Non-Core Web Vital that measures how quickly the parts of the content on a page of visibly filled in during the loading of the page. It is calculated via a frame-by-frame analysis of your page’s loading behavior.

What is a good SI score?

Here is a general rule of thumb for understanding your FCP score:

  • Good: Under 3.4 seconds
  • Mediocre: Between 3.4 and 5.8 seconds
  • Bad: Over 5.8 seconds

Time to Interactive (TTI)

Time To Interactive is a Non-Core Web Vital which measures how long it takes from a page starting to load until the page is fully interactive. 

For a page to be considered fully interactive, it must:

  1. Display usable content (Measured by First Contentful Paint)
  2. Most visible website elements must be loaded
  3. Respond to user interactions in less than 50 ms

What is a good TTI score?

Here is a general rule of thumb for understanding your TTI score:

  • Good: Under 3.8 seconds
  • Mediocre: Between 3.8 and 7.3 seconds
  • Bad: Over 7.3 seconds

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