Optimize images for your website
Complete guide to optimize images for your website: compression, formats, dimensions and best practices for fast loading.
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Images often represent more than 50% of a web page's total weight. Their optimization is therefore essential for your site's performance and SEO.
An unoptimized image can weigh several megabytes and take several seconds to load, driving away visitors and hurting your Google rankings.
In this guide, discover all professional techniques to optimize your web images and improve your loading speed.
Table of contents
Why image optimization matters for SEO
Google uses Core Web Vitals to evaluate site performance. Images directly impact the Largest Contentful Paint (LCP).
A slow site drives away visitors: 53% of mobile users abandon a site that takes more than 3 seconds to load.
Reducing image weight also decreases your bandwidth and hosting costs.
Choosing the right image format
WebP: the best overall choice, 25-35% lighter than JPG with equivalent quality. Compatible with all modern browsers.
JPG: ideal for photos, good size/quality compromise. Use 75-85% quality.
PNG: reserve for images with transparency or simple graphics.
SVG: perfect for logos, icons, and illustrations. Scalable without quality loss.
Advanced optimization techniques
Responsive images: serve different sizes based on device with srcset and sizes.
Lazy loading: load off-screen images only when they come into the viewport.
CDN with optimization: use a CDN that optimizes and resizes images on the fly.
Measuring optimization impact
Use Google PageSpeed Insights to identify images to optimize.
Check Core Web Vitals in Search Console.
Test on a slow connection (Chrome DevTools Network tab) to see the real impact.
Recommended tools
Compress JPG, PNG and WebP images online. Reduce file size up to 90% with no vis...
How to do it in 3 steps
Resize your images to the maximum necessary dimensions (no more than 1920px for banners, 1200px for content).
Upload your images to our compression tool and choose an appropriate quality (75-85% for photos).
Download the optimized images and implement lazy loading on your site.
Common mistakes to avoid
- ✗Uploading full resolution images (4000+ pixels) to display them at 800px.
- ✗Using PNG for photos instead of JPG or WebP.
- ✗Not implementing lazy loading for images below the fold.
- ✗Forgetting to compress CSS background images.
Frequently asked questions
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