Core Web Vitals, explained for founders

Core Web Vitals are three numbers Google uses to judge whether your site feels fast and stable to a real person. They feed into how Google ranks pages, and they map closely to whether visitors stay or leave. Here is what each one means without the jargon.

The three metrics

Largest Contentful Paint (LCP) measures how long the main content takes to appear. Aim for under 2.5 seconds. If your hero image or headline shows up quickly, LCP is usually fine.

Interaction to Next Paint (INP) measures how quickly the page responds when someone taps or clicks. Aim for under 200 milliseconds. A page that freezes for a beat after a tap fails here.

Cumulative Layout Shift (CLS) measures how much the page jumps around as it loads. Aim for under 0.1. If a button moves just as someone goes to tap it, that is CLS.

Why founders should care

Google has said these are a ranking factor, so poor scores can quietly hold back otherwise good content. More directly, slow and jumpy pages lose visitors before they convert. The two problems share a cause and a fix.

What actually moves them

• Ship less. The biggest LCP wins come from smaller images, fewer fonts, and less JavaScript on the critical path.
• Reserve space. Giving images and embeds fixed dimensions stops the layout from jumping, which fixes most CLS.
• Do less work on the main thread. Heavy scripts block interaction. Trimming or deferring them is what improves INP.
• Serve from the edge. Getting HTML to the browser quickly, close to the user, helps every metric.

How we keep them green

We build with these limits in mind from the first commit, not as a cleanup at the end. Server rendered HTML, properly sized images, minimal client side JavaScript, and modern fonts that do not cause layout shift. Good vitals are mostly a result of building carefully, not of bolting on a performance pass later.

You do not need to memorize the numbers. You need a site built so they stay green on their own. That is the default we ship. Talk to us.