Learn the best techniques to reduce image file sizes while maintaining visual quality for faster loading websites.
Images are typically the heaviest assets on any webpage. A single unoptimized photograph can weigh several megabytes, which translates directly into slower load times, higher bounce rates, and lower search engine rankings. According to Google, pages that load in under 2 seconds have a 9% lower bounce rate than slower pages, and images account for over 50% of the average webpage's total weight (HTTP Archive, 2024). Compressing your images before publishing them is one of the highest-leverage steps you can take to improve your site's performance.
There are two fundamental approaches to image compression. Lossless compression reduces file size without discarding any pixel data. PNG and WebP support lossless compression and are ideal for logos, icons, and screenshots where crisp edges matter. Lossy compression, used by JPEG and WebP in lossy mode, discards some image data that the human eye is unlikely to notice. For photographs, a quality setting between 70–85% typically produces a file 50–80% smaller than the original with no perceptible visual difference.
Modern browsers support WebP, which offers superior compression compared to JPEG and PNG for both photos and graphics. WebP images are on average 30% smaller than JPEG at equivalent visual quality (Google Developers). AVIF is an even newer format with up to 50% better compression than JPEG, though browser support is still catching up. As a practical rule: use WebP for most images, JPEG for legacy compatibility with photographs, PNG only when you need transparency without quality loss, and SVG for icons and simple illustrations.
Beyond format and quality, there are several additional steps that compound your savings. Always resize images to the dimensions they will actually be displayed at. Use lazy loading so images below the fold are not fetched until the user scrolls to them. Our free Image Compressor tool lets you drag and drop images and compress them directly in the browser without uploading anything to a server.