Use WebP as your default format for all web images — it offers 25-35% smaller file sizes than JPEG with the same quality. For browsers that do not support WebP, provide JPEG fallbacks using the HTML picture element. Use PNG only when you need transparency and WebP is not an option. Avoid BMP and TIFF entirely for web use. For icons and simple graphics, consider SVG which scales infinitely and has tiny file sizes. Our Image Converter makes format conversion effortless.

Never serve a 4000px image when it will only display at 800px on screen. Resize images to match their maximum display dimensions. For responsive designs, create multiple sizes and let the browser choose. A good rule of thumb: hero images at 1920px wide, content images at 1200px, thumbnails at 400px. Use our Image Resizer to create these size variations quickly. Remember that retina displays need 2x resolution, so a 400px thumbnail should be served at 800px for sharpness on high-DPI screens.

For photographs, JPEG quality between 75-85% is the sweet spot for web use. Below 75%, artifacts become visible. Above 85%, file size increases dramatically with minimal quality gain. For graphics with text or solid colors, PNG-8 or WebP lossless may be smaller than JPEG. Use our Image Compressor to find the perfect quality setting for each image. Consider using the target-size mode to hit exact file size budgets, especially when working with design constraints.

Use the HTML picture element with srcset to serve different image sizes based on screen width. This ensures mobile users do not download desktop-sized images. Use loading=lazy on images below the fold to defer loading until they are needed. Consider using a CDN with automatic image optimization like Cloudflare or Imgix. For critical above-the-fold images, preload them in the document head to improve Largest Contentful Paint.

Use Google PageSpeed Insights and Lighthouse to measure your image optimization impact. Aim for a Largest Contentful Paint under 2.5 seconds. Monitor your Core Web Vitals in Google Search Console. Test your site on real mobile devices, not just desktop browsers. Keep a spreadsheet of your image sizes and target budgets. Revisit optimization quarterly as your content grows. Our tools make it easy to re-optimize your entire image library whenever needed.