What Are Core Web Vitals? (And Why Google Cares About Them)

Core Web Vitals are three scores Google uses to grade how *fast* and *smooth* your website feels to people. Google uses these scores to decide where you show up in search results.

The three big ones are LCP, INP, and CLS. They sound like boring math homework, but they are actually pretty simple ideas.

LCP: Largest Contentful Paint

LCP measures how fast your main content shows up.

Imagine your website is a stage. LCP is the time it takes for the lead actor (the biggest image or headline) to walk out and stand under the spotlight. Google wants this to happen in 2.5 seconds or less.

If your LCP takes more than 4 seconds, people will think your site is broken and leave.

Why LCP gets slow:

• Giant photos that take forever to download (like 5MB files)
• A slow "brain" (the server) taking too long to send data
• Code that tells the browser to "wait" before showing anything
• Fancy fonts that take a while to pop up

How to fix it:

• Shrink your big photos to under 200 KB using modern formats like WebP
• Use a CDN (a Content Delivery Network, which is like having a copy of your site in every big city so it's closer to your visitors)
• Tell the browser to load important images first
• Make non-essential code wait its turn

INP: Interaction to Next Paint

INP measures how fast your site reacts when you click or tap something.

You tap a "Buy Now" button. How long does it take for the site to actually move? INP is that tiny pause. Google wants this to be under 200 milliseconds—faster than the blink of an eye.

Why INP gets slow:

• Too much JavaScript (the code that makes things interactive) clogging up the pipes
• Too many "extra" things like chat bots, tracking pixels, or ads
• Complex apps trying to do too much math all at once

How to fix it:

• Delete any extra scripts or widgets you don't actually use
• Tell the browser to handle the "action" part of your code later
• Break big coding tasks into smaller pieces so the site doesn't "freeze"
• Let the server do the heavy lifting instead of the user's phone

CLS: Cumulative Layout Shift

CLS measures how much your page jumps around while it's loading.

You’re halfway through reading a sentence when suddenly a big ad pops in, pushes the text down, and you lose your place. That "jump" is a layout shift. It's super annoying. Google wants your CLS score to be under 0.1.

Why CLS happens:

• Images that don't tell the browser how big they are before they load
• Ads that suddenly appear and shove everything else out of the way
• New fonts that are a different size than the "normal" ones
• Banners that drop down from the top after the page looks finished

How to fix it:

• Always tell the computer the exact width and height of your images
• Build a "box" or placeholder for ads to sit in so they don't push text around
• Use a setting called font-display: optional so fonts don't wiggle the text
• Make sure nothing new "pops in" at the top of the screen after the page starts

How to check your Core Web Vitals

Here are three free ways to see your grades:

1. PageSpeed Insights — Paste your link and it gives you a report card with a "to-do" list. 2. Google Search Console — This shows you how your whole site is doing over time. 3. Chrome DevTools — Right-click your page, go to "Inspect," then "Performance" to see exactly what is slowing things down.

Or, try our website audit for a simple version that tells you exactly what to fix first.

What "passing" Core Web Vitals means

Google looks at your real visitors over the last month. If 75% of those people had a "Good" experience, you pass.

| Metric | Good | Needs work | Poor | |--------|------|---------------------|------| | LCP (Speed) | 2.5s or less | 2.5–4s | Over 4s | | INP (Responsiveness) | 200ms or less | 200–500ms | Over 500ms | | CLS (Stability) | 0.1 or less | 0.1–0.25 | Over 0.25 |

Why this matters

If your site fails these tests, Google might move you further down the search results. Plus, when a site is slow or jumpy, people get frustrated and leave.

Core Web Vitals aren't the only thing that matters, but they are something you can actually fix. Get these scores right once, check them every month, and you won't have to worry about a slower competitor taking your spot.