Core Web Vitals: What They Are and How to Improve Them

Introduction

Core Web Vitals are the three metrics Google uses to measure a website’s real user experience. Since 2021 they’ve been part of Google’s algorithm, so they directly influence your ranking.

If your website doesn’t pass the Core Web Vitals, Google ranks you lower. If you pass them, you have an advantage over competitors who don’t care about them. In this article you’ll see what each one is and how to improve it.

What Core Web Vitals are

Core Web Vitals are three metrics that measure concrete aspects of user experience:

Metric	What it measures	Google’s goal
LCP (Largest Contentful Paint)	How fast the main content loads	< 2.5s
INP (Interaction to Next Paint)	How fast the website responds to interaction	< 200ms
CLS (Cumulative Layout Shift)	How visually stable (whether it “jumps”)	< 0.1

Google classifies websites as “good”, “needs improvement” or “poor” based on these three values. Being “good” in all three is the goal.

[Imagen sugerida: screenshot of Search Console showing Core Web Vitals status]

LCP: main content must load fast

LCP (Largest Contentful Paint) measures how long it takes to load the largest visible element on screen. It’s usually a large image (a banner, a featured photo) or a text block.

Goal

• Good: less than 2.5 seconds.
• Needs improvement: between 2.5 and 4 seconds.
• Poor: more than 4 seconds.

How to improve LCP

1. Optimize the main image. Compress it and serve it in WebP format.
2. Reduce server response time (TTFB). A good host with LiteSpeed and NVMe helps a lot.
3. Eliminate render-blocking resources. CSS and JavaScript that stop loading.
4. Use a CDN to serve files closer to the user.
5. Preload the main image with <link rel="preload">.

INP: the website must respond quickly to touch

INP (Interaction to Next Paint) measures how long it takes the website to respond when the user interacts: clicks a button, opens a menu, fills a field.

INP replaced FID (First Input Delay) in March 2024.

Goal

• Good: less than 200ms.
• Needs improvement: between 200 and 500ms.
• Poor: more than 500ms.

How to improve INP

1. Reduce JavaScript. The less JS, the faster it responds.
2. Break long JavaScript into smaller tasks.
3. Defer non-essential JavaScript with defer or async.
4. Use a good cache plugin that serves static pages.
5. Limit plugins that add unnecessary JavaScript.

INP is the hardest metric to improve on websites with many plugins (like poorly optimized WordPress). The key is less JavaScript.

CLS: the website must not “jump”

CLS (Cumulative Layout Shift) measures how much page elements move while loading. It’s the annoying effect of a text, image or button suddenly changing position.

Goal

• Good: less than 0.1.
• Needs improvement: between 0.1 and 0.25.
• Poor: more than 0.25.

Examples of high CLS

• You’re reading text and, suddenly, an image that loads above pushes you down.
• You’re about to click a button and, just then, a banner appears that moves the button.
• A web font loads and pushes all the text.

How to improve CLS

1. Always indicate image and video dimensions. Use the width and height attributes.
2. Reserve space for ads. If you show ads, leave a fixed slot.
3. Don’t insert content above existing content. Except for intentional animations.
4. Load web fonts correctly. Use font-display: swap or preload the font.
5. Avoid banners that appear late. If you put a fixed banner at the top or bottom, have it take its space from the start.

How to measure your Core Web Vitals

From Search Console

Google Search Console has a Core Web Vitals section that tells you how many URLs on your website are in good, needs improvement or poor status. It’s the most reliable source because it uses real user data.

[Imagen sugerida: screenshot of the Core Web Vitals report in Search Console]

From PageSpeed Insights

Enter your URL in PageSpeed Insights and you’ll see your LCP, INP and CLS values, both from field and lab data.

From the browser

Chrome includes the Performance tab in developer tools, where you can see these metrics while browsing.

Useful tips

• Start with the worst metric. If your CLS is poor and your LCP is good, work on CLS first.
• Measure on mobile, not just desktop. Google prioritizes the mobile version.
• Don’t chase a perfect 100. Being “good” in all three metrics is already a solid goal.
• Review after installing plugins. Each plugin can affect Core Web Vitals.
• Combine optimization with good hosting. A well-optimized website on slow hosting is still slow.

Common problems

I improve LCP but CLS gets worse

Changing an image may change its size and cause shifts. Always make sure to define width and height.

I have a good PageSpeed score but poor Search Console

PageSpeed measures one specific URL at one moment. Search Console measures many URLs with accumulated real data. What matters to Google is Search Console.

INP is very hard to improve

INP depends mainly on JavaScript. If you use WordPress with many plugins, the path is to reduce plugins and use an optimization plugin that delays unnecessary JS.

My Core Web Vitals are good but I don’t rank higher on Google

Core Web Vitals are one of Google’s 200 ranking factors. Improving them helps, but SEO also depends on content, links, authority and other factors.

I don’t have field data in PageSpeed

Websites with little traffic may not have enough field data (Chrome needs a minimum of users). Use lab data while you accumulate traffic.

Frequently asked questions

Do Core Web Vitals affect SEO?

Yes, directly. Google has used them as a ranking factor since 2021. Moving from “poor” to “good” can mean an increase in traffic.

Which is the most important metric?

All three matter, but LCP usually has the most impact on the perception of speed.

Do I need a plugin to improve Core Web Vitals?

In WordPress, an optimization plugin (like LiteSpeed Cache, WP Rocket or W3 Total Cache) helps a lot. But there are also things done in the theme or manually.

Does my hosting influence Core Web Vitals?

Yes, especially LCP. Server response time (TTFB) depends on hosting and directly affects LCP. A hosting with LiteSpeed and NVMe noticeably improves this metric.

Does Google change Core Web Vitals?

Yes. In March 2024 Google replaced FID with INP. It’s important to stay up to date, because what they didn’t measure before they do now.

Care for the experience and Google will reward you

Core Web Vitals are Google’s way of measuring whether your website offers a good real experience to users. Improving LCP, INP and CLS not only helps your SEO, but also improves the satisfaction of those who visit you.

If your website doesn’t pass Core Web Vitals due to slow hosting, at miHosting we offer plans with LiteSpeed, NVMe SSD and native caching that noticeably reduce LCP. Open a ticket from your client panel and we’ll help you diagnose and improve your metrics.