How to Pass Core Web Vitals with WebP and Image Compression 2026
New2026-02-011 min read1 tool
Improve LCP and CLS with image compression and WebP. Technical guide for site owners.
What Are Core Web Vitals?
LCP (Largest Contentful Paint), FID (First Input Delay), CLS (Cumulative Layout Shift). Google uses them to rank sites.
The Role of Images in Performance
Large images slow down LCP. Use WebP or compressed JPG. Right dimensions for the viewport.
Image Strategy for Fast Sites
Compress to 80–85%. Use WebP with JPG fallback. Responsive dimensions.
Frequently Asked Questions
- What is LCP?
- LCP (Largest Contentful Paint) measures how long it takes for the largest visible element—usually an image or text block—to appear. Google uses it for ranking. Target under 2.5 seconds. Compress images and use WebP to improve LCP.
- How do images affect Core Web Vitals?
- Large images slow LCP and can cause CLS (layout shift) if dimensions are not set. Compress to 80–85%, use WebP with JPG fallback, and set width/height on img tags. Lazy load below-the-fold images to reduce initial load.
- What is a good LCP score?
- Good LCP is under 2.5 seconds. Under 4 seconds is acceptable. Over 4 seconds is poor. Images are often the culprit. Compress hero images, use responsive dimensions, and consider CDN delivery for large sites.