Core Web Vitals Quiz

9 questions on core web vitals, each with an explanation. Free, no signup.

About the core web vitals questions

Core Web Vitals are the three user-experience metrics Google measures on real page loads: Largest Contentful Paint for loading, Interaction to Next Paint for responsiveness, and Cumulative Layout Shift for visual stability. Each has a threshold that separates good from needs-improvement from poor.

This track checks whether you know what each metric measures, the thresholds, the lab metrics that sit beside them (FCP, TBT, TTI, Speed Index) and the page problems that push each one into the red.

This track has 9 questions. Learning mode asks 9 at a time with the explanation after every answer; the timed challenge asks 9 in 100 seconds. Free, no signup, and a different draw every time you retake it.

Sample questions from this track

8 of the 9, with the answer and the explanation hidden until you open each one.

What is Largest Contentful Paint (LCP)?Core Web Vitals · Beginner
  1. A The time it takes for the page to become interactive
  2. B The time until the first byte of data is received
  3. C The time it takes for the largest visible element to load
  4. D The time it takes for all images to load completely

Answer: C. LCP measures loading performance by tracking when the largest content element in the viewport becomes visible. A good LCP is 2.5 seconds or less.

What is a good LCP score?Core Web Vitals · Beginner
  1. A Under 2.5 seconds
  2. B Under 1 second
  3. C Under 4 seconds
  4. D Under 5 seconds

Answer: A. Google recommends an LCP of 2.5 seconds or less for a good user experience. Scores between 2.5-4 seconds need improvement, and over 4 seconds is poor.

What affects LCP the most?Core Web Vitals · Advanced
  1. A JavaScript execution time and file size
  2. B CSS file size and loading order
  3. C Number of HTTP requests made
  4. D Server response time and large images

Answer: D. LCP is most affected by slow server response times, render-blocking resources, and large images or videos. Optimizing these elements significantly improves LCP.

What does CLS measure?Core Web Vitals · Beginner
  1. A Content Loading Speed
  2. B Cumulative Layout Shift
  3. C Client-Side Latency
  4. D Cache Loading System

Answer: B. CLS (Cumulative Layout Shift) measures visual stability by tracking unexpected layout shifts. A good CLS score is less than 0.1.

What is First Input Delay (FID)?Core Web Vitals · Advanced
  1. A Time from user interaction to browser response
  2. B Time until first paint renders
  3. C Time until page is interactive
  4. D Time to download first resource

Answer: A. FID measures interactivity by tracking the time from when a user first interacts with your page to when the browser can respond. Good FID is less than 100ms.

What is INP (Interaction to Next Paint)?Core Web Vitals · Advanced
  1. A The delay between consecutive page paint events
  2. B A network protocol for interactive applications
  3. C The time required to load the next page section
  4. D A Core Web Vital measuring overall page responsiveness

Answer: D. INP is a newer Core Web Vital that replaces FID. It measures responsiveness by observing all interactions throughout the page's lifecycle. Good INP is less than 200ms.

What is the First Contentful Paint (FCP)?Core Web Vitals · Beginner
  1. A The time when the entire page has loaded fully
  2. B The time when the first text or image renders
  3. C The time to interactive for all user input
  4. D The time when all CSS is loaded completely

Answer: B. FCP measures when the first text, image, or canvas element is rendered on the screen. Good FCP is 1.8 seconds or less. It's an important loading performance metric.

What is Total Blocking Time (TBT)?Core Web Vitals · Advanced
  1. A Total time main thread is blocked from input
  2. B Time when the website is offline completely
  3. C Time spent by search bots on your site
  4. D The duration of server downtime and issues

Answer: A. TBT measures the total time between FCP and Time to Interactive when the main thread is blocked long enough to prevent input responsiveness. Lower TBT means better interactivity.

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