Core Web Vitals Checklist 2026: Everything You Need to Pass

Passing Google's Core Web Vitals assessment is no longer optional. It is a confirmed ranking factor, and as of 2026, Google's algorithms place even more weight on page experience signals. This checklist covers every metric, every threshold, and every optimization you need to pass.

The Three Official Core Web Vitals

1. LCP (Largest Contentful Paint)

What it measures: The time it takes for the largest visible content element to render.

Thresholds:

• Good: Under 2.5 seconds
• Needs improvement: 2.5 to 4.0 seconds
• Poor: Over 4.0 seconds

Checklist to pass LCP:

• ☐ Hero image is compressed and served in WebP or AVIF format
• ☐ Hero image has explicit width and height attributes
• ☐ Hero image uses fetchpriority="high" and loading="eager"
• ☐ LCP image is preloaded with <link rel="preload">
• ☐ No lazy loading on above-the-fold images
• ☐ Critical CSS is inlined in the document head
• ☐ Non-critical CSS is deferred
• ☐ Render-blocking JavaScript is eliminated or deferred
• ☐ Server response time (TTFB) is under 800ms
• ☐ CDN is configured for static assets
• ☐ Server-side caching is enabled for dynamic pages

For a detailed walkthrough of every LCP fix, read our complete LCP optimization guide.

2. CLS (Cumulative Layout Shift)

What it measures: How much the page layout shifts unexpectedly during loading and interaction.

Thresholds:

• Good: Under 0.1
• Needs improvement: 0.1 to 0.25
• Poor: Over 0.25

Checklist to pass CLS:

• ☐ All images have explicit width and height attributes
• ☐ All video and iframe embeds have explicit dimensions
• ☐ Ad slots and dynamic content have reserved space
• ☐ Web fonts use font-display: swap or font-display: optional
• ☐ Font files are preloaded to minimize swap visibility
• ☐ No content is dynamically injected above existing content
• ☐ Animations use CSS transform instead of changing layout properties
• ☐ Cookie banners and notification bars have reserved space or use fixed positioning

Common CLS traps:

• Images loaded without dimensions cause the page to jump when they render
• Third-party ad scripts that inject content at unpredictable times
• Cookie consent banners that push page content down
• Font loading that causes text to reflow

3. INP (Interaction to Next Paint)

What it measures: The responsiveness of your page to user interactions (clicks, taps, key presses) throughout the entire page session.

Thresholds:

• Good: Under 200 milliseconds
• Needs improvement: 200 to 500 milliseconds
• Poor: Over 500 milliseconds

Checklist to pass INP:

• ☐ No long tasks (over 50ms) blocking the main thread
• ☐ JavaScript bundles are code-split and loaded on demand
• ☐ Event handlers are lightweight and do not trigger expensive computations
• ☐ Heavy processing is offloaded to Web Workers
• ☐ Third-party scripts are loaded with async or defer
• ☐ DOM size is under 1,500 elements (ideally under 800)
• ☐ No synchronous layout thrashing (reading and writing DOM properties in loops)
• ☐ React/framework hydration is optimized (partial hydration or progressive hydration where possible)

INP debugging tip: Use Chrome DevTools Performance tab to record interactions. Look for long tasks in the main thread flame chart. The task running when your interaction fires is the one causing poor INP.

Additional Metrics to Monitor

TTFB (Time to First Byte)

While not an official Core Web Vital, TTFB directly affects LCP.

• Target: Under 800ms
• Checklist:
• [ ] Server-side caching is enabled
• [ ] CDN is configured with edge caching
• [ ] Database queries are optimized and indexed
• [ ] DNS resolution is fast (consider DNS prefetching)
• [ ] TLS handshake is optimized (HTTP/2 or HTTP/3, TLS 1.3)
• [ ] Hosting infrastructure can handle your traffic

Total Blocking Time (TBT)

TBT is a lab metric that correlates closely with INP. It measures the total time the main thread was blocked during page load.

• Target: Under 200ms
• Primary fix: Reduce and defer JavaScript execution

What Changed in 2026

The most significant recent change to Core Web Vitals was the replacement of First Input Delay (FID) with Interaction to Next Paint (INP) in March 2024. This change made the responsiveness metric much more demanding because INP measures all interactions, not just the first one.

As of 2026, Google has also increased the weight of page experience signals in its ranking algorithm. While exact weights are not public, multiple studies have shown stronger correlations between Core Web Vitals pass rates and ranking improvements compared to previous years.

Additionally, AI-powered search engines like Google's AI Overviews tend to favor fast-loading pages when selecting sources to cite. Optimizing Core Web Vitals helps you perform better in both traditional and AI search results.

Tools to Check Each Metric

For a comparison of speed testing tools, see our PageSpeed Insights vs FixRoast guide.

The Quick-Start Fix Priority

If you are failing Core Web Vitals and need to prioritize, here is the order that delivers the fastest results:

1. Fix LCP first. It has the biggest impact on user experience and is the most commonly failed metric. Compress images, preload the hero, and defer render-blocking resources.
2. Fix CLS second. Add dimensions to all images and embeds. Reserve space for ads and dynamic content.
3. Fix INP third. Audit your JavaScript, break up long tasks, and defer non-critical scripts.

Each fix builds on the previous one. Faster server response helps LCP. Fewer scripts help both LCP and INP. Proper image handling helps both LCP and CLS.

Verify Your Progress

After working through this checklist, test your site again:

1. Run the FixRoast Page Speed Test for an AI-powered analysis with prioritized next steps
2. Check Google Search Console after 28 days to see field data improvements
3. Monitor your rankings for changes over the following 4 to 8 weeks

If you want a complete analysis beyond just speed, including design, copywriting, and user experience, try the full FixRoast landing page roast. Optimizing Core Web Vitals is essential, but it is just one piece of a high-converting landing page.