Web Vitals – Google’s factors for the user experience
The Core Web Vitals are a series of specific factors that Google classifies as decisive for the user experience of a website.
They are made up of three specific measurements:
- Loading time (Largest Contentful Paint)
- Interactivity (First Input Delay)
- Visual stability (Cumulative Layout Shift)
What are Core Web Vitals?
In short, Core Web Vitals are a subset of factors that Google uses to evaluate the “Page Experience”. They are Google’s way of objectively evaluating the overall UX of your site.
The initiative at a glance
Web Vitals is a Google initiative. Its aim is to provide standardized guidance for quality signals. These are essential for a great user experience on the internet.
Over the years, Google has released many tools to measure performance. Some developers are experts at using them. Others, however, have found the plethora of tools and metrics confusing.
The good news: website owners don’t have to be performance gurus. The Web Vitals initiative simplifies the landscape. It helps webmasters focus on the metrics that matter most.
The three key figures
Core Web Vitals apply to all websites. They should be measured by every website owner and appear in all Google tools. Each metric represents a specific facet of the user experience.
The current set focuses on three aspects: Loading time, interactivity and visual stability.
1st Largest Contentful Paint (LCP)
This measures the charging power. It is about when the main content is charged.
- Target: The LCP should occur within 2.5 seconds.
2. first input delay (FID)
This measures interactivity. It is about how quickly the page responds to user input.
- Target: The page should have an FID of less than 100 milliseconds.
3. cumulative layout shift (CLS)
This measures visual stability. It checks whether elements shift unexpectedly during loading.
- Target: The page should have a CLS of less than 0.1.
The threshold: Google uses the 75th percentile to ensure that you meet the targets. This means that if 75% of your page views (mobile and desktop) reach the targets, the test is considered passed.
How do you measure Core Web Vitals?
Since Google considers these values to be the backbone of the user experience, the company provides various tools. Here are three ways to measure it:
1st Chrome User Experience Report (CrUX)
Google collects anonymized data from real users. This is called “field data”.
- Advantage: You don’t have to set anything up. Google already has the data.
- tools: PageSpeed Insights uses this database.
- Disadvantage: The analysis is not very detailed. It often does not help to accurately diagnose specific problems on a single subpage.
2. use of JavaScript
You can use JavaScript to measure the values directly.
- Library: Google offers a web vitals library with ready-made APIs.
- Browser extension: The “Web Vitals” extension is available in the Chrome Web Store. This allows you to see the values directly in the browser without having to write code.
3. lab tools
Lab tools simulate a page view under controlled conditions.
- Use: Particularly helpful before a website goes live (pre-launch).
- Important: Do not neglect the field data (real users). The experience of a real user is influenced by factors such as network conditions or slow devices. Use lab tools for development and field data for monitoring.