Online Tool Store
Core Web Vitals Glossary
A quick reference for the Core Web Vitals metrics — LCP, INP, CLS, and related signals — with a plain-language definition and the threshold Google considers good for each. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Reference
Core Web Vitals Glossary
| Metric | Measures | Good threshold |
|---|---|---|
| LCP | Time until the largest visible element renders | ≤ 2.5s |
| INP | Responsiveness — delay from interaction to next paint | ≤ 200ms |
| CLS | How much visible content shifts unexpectedly | ≤ 0.1 |
| FCP | Time until the first content paints on screen | ≤ 1.8s |
| TTFB | Time until the first byte of the response arrives | ≤ 0.8s |
How it works
- Scan the table for the metric you're looking up.
- Read its plain-language definition and what counts as "good."
- Copy the whole glossary for quick reference elsewhere.
FAQ
Which metrics count as Core Web Vitals?
Google's current set is LCP (loading), INP (interactivity), and CLS (visual stability). FCP and TTFB are closely related performance metrics often measured alongside them.
Do Core Web Vitals affect search ranking?
Yes — they're one of many ranking signals Google uses, part of what it calls "page experience." They're not the only factor, but consistently poor scores can work against you.
What replaced FID as a Core Web Vital?
INP (Interaction to Next Paint) replaced FID (First Input Delay) as the official responsiveness metric in March 2024 — INP measures the full interaction, not just the initial delay.
How we compare
| Feature | Online Tool Store | web.dev's full documentation | Searching each term individually |
|---|---|---|---|
| All five metrics on one page | Yes | Spread across pages | No |
| Quick reference, not a deep dive | Yes | No — very detailed | Varies |
| Copyable summary | Yes | No | No |
For a fast refresher on what each metric means and its threshold, this beats searching each term one at a time.