Core Web Vitals, explained for founders
Demo content — a placeholder explainer post. No client metrics are referenced here.
Core Web Vitals are three measurements Google uses to judge whether a page feels fast and stable to a real visitor. You don't need to be an engineer to understand what they mean for the business.
Largest Contentful Paint (LCP)
LCP measures how long it takes the biggest visible element — usually a hero image or heading — to render. Slow LCP means visitors stare at a blank or half-loaded page before they see anything worth reading.
Interaction to Next Paint (INP)
INP measures how long the page takes to respond after someone clicks, taps, or types. A page can look finished and still feel broken if INP is bad — buttons that don't respond for half a second train visitors to stop trying.
Cumulative Layout Shift (CLS)
CLS measures how much content jumps around as a page loads. The classic case: you go to tap a button and an ad loads above it, shifting the whole page down at the last second.
Why this is a founder problem, not just a developer one
- All three vitals are search ranking signals
- All three also correlate directly with conversion rate
- Fixing them after launch is more expensive than designing around them from the start
A one-second delay in page load can measurably reduce conversions — which is why these numbers belong in a board deck, not just a dev ticket.
For the full technical definitions, the canonical source is web.dev's Core Web Vitals overview.
The short version: Core Web Vitals aren't a developer's vanity metric. They're a proxy for whether a visitor's first experience of the site is fast and stable enough to trust with a purchase or a signup.