Complete Guide to Image Compression for Web — Faster Loading Pages
Page speed is a Google ranking factor, and images are the biggest culprit. A single uncompressed hero image can add 3–5 seconds to load time. Here is everything you need to know.
Compress Images Free →Why image compression matters for SEO
Google uses Core Web Vitals — especially Largest Contentful Paint (LCP) — as a ranking signal. LCP measures how long the largest image on screen takes to load. Unoptimised images are the leading cause of poor LCP scores. Compressing images typically improves LCP by 30–60%.
Lossy vs lossless — which to use?
Lossy compression removes some image data. At 80–85% quality, the result looks identical to the human eye but is 60–70% smaller. Use lossy for all web photographs.
Lossless compression reduces file size without removing any pixels — typically 15–30% savings. Use lossless for logos, icons, and graphics where pixel precision matters.
Best quality settings per format
- JPG: Quality 80–85% — visually identical to 100%, 60% smaller
- WebP lossy: Quality 80% — 25% smaller than JPG 85% at the same visual quality
- PNG: Always lossless — switch to WebP for smaller files
Step-by-step compression workflow
- Resize the image to the actual display size first (never upload a 4000px image that displays at 800px)
- Convert to WebP format using the JPG to WebP converter
- Compress at 80% quality using the Image Compressor
- Strip EXIF data using the EXIF Remover (saves 50–100KB per photo)
Before uploading to your website
Run your images through this checklist: dimensions match display size, file is WebP or compressed JPG, EXIF metadata removed, file name uses hyphens not underscores (image-compression-guide.webp not imageCompressionGuide.webp).
What is the ideal image file size for web?
Under 100KB for most images. Hero images can go to 200KB. Thumbnails and icons should be under 30KB. Use the Image Compressor to target these sizes.
Does compression affect image quality?
At 80–85% quality, no visible difference exists. Only when you go below 70% do compression artifacts become noticeable — blocky areas, colour banding in gradients.
Should I compress PNG files?
Use lossless PNG compression for graphics, or switch to WebP for best results. Lossy PNG compression causes visible colour banding on flat-colour images.