Google is including three new rules to their SEO stack, in a package they call Core Web Vitals. Let’s review them here, and see why they are important for a better web.
Largest Contentful Paint (LCP)
LCP measures the loading performance, by measuring how much time the most important element on the page takes to load. If that element loads in 2.5s or less, it’s considered fast enough for a good user experience.
How does Google determine what the most important element on the page is? They take in account only some elements:
- Background images (gradients are not considered images)
- Blocks of content, containing primarily text
Then, from that list, the largest one on the page will be the LCP. This element can change while the page is loading. Here’s an example:
Notice that LCP is different from FCP (First Contentful Paint), which is the first element considered “content” to load.
First Input Delay (FID)
FID measures interactivity within the page. In order to provide a great user experience, pages should strive to have a First Input Delay of 100ms or less. Yes, that ms means milliseconds. But what’s FID?
An example to differentiate processing time from FID is a contact form. A contact form may take a few seconds to send your inquiry, but when you click on “Send”, you know you’ve clicked it and it’s processing. FID is the measure that delay between you clicking the Send button and when it actually starts processing your inquiry. That’s why it needs to be 100ms or less, more would be annoying to the user, as the user expects their actions to have an immediate reaction.
Now that might arise the question: “Why only the first interaction is considered?” Google gives several reasons:
- FID will be your user’s first impression from how the page works. If a page loads fast (good LCP), but then it gets choppy when they interact with it, that’s a bad user experience.
- Performance’s most critical scenario is usually while loading the page, since there are a lot of things going on. By measuring the worst case, we can have some certainty that your page will stay snappy afterwards.
Not everything counts as an Interaction for this new metric. Only discrete interactions are valid, such as clicks, taps or key presses. Zooming or scrolling are discarded, since those can have other separate performance issues (such as the device not being able to handle a fast scroll in time).
Cumulative Shift Layout (CLS)
CLS measures visual stability. In order to provide a great user experience, pages should strive to have a CLS score of 0.1 or less. But what is CLS?
Have you ever been reading something online, and suddenly, something else loads and the text moves, and you lose track of where you were reading? Or perhaps, you are about to click on something, and that something moves the second you place your finger on it, and you accidentally click on something else.
These experiences can range from annoying to a real problem. Check out this example:
CLS measures how that annoying is your website to use, by looking at the sum of all the layout shifts your page suffers from. A layout shift happens when, as we saw on the example above, some of the content jumps from one place to another. It is measured by two different components: Impact Fraction and Distance Fraction. The impact fraction is the fraction of the screen that is affected by the layout shift.
The impact fraction is, in this case, 75%, as it covers the 75% of the screen. This is 0.75.
Then the Distance Fraction is the distance that the element moves. In this case, the box moves 25% down. This is 0.25.
CLS is then
0.75*0.25 = 0.1875. This is already more than the 0.1 Google recommends, so we could say that’s a bad experience for the user.
The other Page Experience Signals
LCP, FID and CLS are the new metrics, but there are other signals to measure Page Experience that Google is already considering:
- Mobile-friendliness: Your page should be adapted to be used on smartphones. More than half the traffic of the web comes from mobile devices, so this is important for your users.
- Safe-browsing practices: Your page shouldn’t be hosting viruses, malware or trying to scam people.
- HTTPS: Your page is served with a secure and up-to-date SSL/TLS certificate by default.
- No intrusive interstitials: Your page doesn’t serve an ad before the content shows.
When will the new metrics affect my page ranking?
This is Google’s roadmap:
- May 2021: Google will start measuring the new Core Web Vitals.
- Mid-June 2021: Google will start taking in account the new Core Web Vitals for rankings.
- End of August 2021: Google will put more weight into these metrics, further affecting rankings.
Even if it’s called the May 2021 update, this won’t start affecting your page ranking until mid-June 2021.
Regardless of all these changes, content quality will still be the king. It won’t matter if your page is fast to load, fast to interact with, and is super smooth to use. If your content doesn’t attract and retain users, they won’t even experience how good of a web you have.
However, if you already have that content your users are looking for, these new metrics will be useful to rank you up and differentiate from your competitors with similar content, as you will rank higher the better the experience.