How fast should your website be? Core Web Vitals in plain English
“Make it faster” is easy to say and hard to measure. Google publishes three measurements, called Core Web Vitals, with clear targets. Here’s what they mean without the jargon.
Arthur, ELMFOLD · Southampton · · 7 min read
The three numbers
| Measure | In plain English | Google’s ‘good’ target |
|---|---|---|
| LCP, Largest Contentful Paint | How long until the main thing on screen appears | 2.5 seconds or less |
| INP, Interaction to Next Paint | How quickly the page reacts when you tap | 200 milliseconds or less |
| CLS, Cumulative Layout Shift | How much things jump around while loading | 0.1 or less |
Google measures these on real visitors’ devices, and phones are what most of your visitors use, so the phone numbers are the ones to watch.
Why speed is a money question
Slow pages lose people before they’ve seen anything. Published research has repeatedly linked faster pages with more sales and enquiries, and anyone who has waited for a product photo on bad signal knows why.
Speed also affects search: it’s one of the signals Google uses, and a slow site wastes the visits you worked to get.
Time your site and see what slow costsFree, automatic, about a minute→The fixes that matter most
- Size images for the screen. The biggest single win on most sites: a phone doesn’t need a 4,000-pixel photo.
- Load the first image first. Tell the browser which picture matters, and load the rest as people scroll.
- Cut scripts that don’t help someone buy. Chat widgets, old app code, tracking you don’t use.
- Fewer fonts. Two families, only the weights you use.
- Reserve space for things that load late, like banners and images, so nothing jumps.
- Fewer apps. On Shopify, each app often adds code to every page, even after you stop using it.
How to check your own site
Use the free tools on this site: the Website X-ray times your site on a phone and a desktop and ranks what’s slowing it down, and “What slow costs you” turns your measured speed into a rough cost using your own numbers.
Questions people ask
What is a good page load time?
For the main content, 2.5 seconds or less on a phone is Google’s published ‘good’ target for Largest Contentful Paint.
Do Core Web Vitals affect Google rankings?
They are one of the page experience signals Google uses. Content and relevance matter more, but speed affects whether visitors stay.
Why is my Shopify store slow?
Usually large images, too many apps and theme features you don’t use. All three are fixable without starting again.
Want me to look at yours?The free project plan takes about four minutes and gives you a written plan with a fixed price. You keep it whether or not we work together.
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