An image that is perfect for a website may be too small for print, and a print-ready image may be painfully heavy on a website. The reason is simple: print and web solve different problems. Print needs enough detail for physical output. Web needs fast loading and broad compatibility on screens.
For the web, pixel dimensions matter most. For print, physical dimensions and print density matter. A 1200-pixel image can look excellent in a blog post but soft on an A4 flyer. A 5000-pixel image can print beautifully but slow down a mobile web page.
Choose web exports for screens
For websites, resize to the largest display size the layout needs. Use JPG or WebP for photos and PNG for transparency or crisp UI graphics. Compress aggressively enough to improve speed but not so much that artifacts distract from the content.
Web images also need predictable compatibility. JPG works almost everywhere. PNG works everywhere and keeps transparency. WebP is excellent for modern websites but may not be accepted by every CMS, marketplace or email tool.
Keep high-quality masters for print
For print, avoid repeated lossy conversions. Keep the highest-quality source you have and only create compressed web copies from it. If a print service asks for JPG, export once at high quality. If it asks for PNG or PDF, follow that requirement instead of guessing.
The safest habit is to separate masters from delivery files. Store the original or print-ready image separately, then generate web versions, thumbnails and social crops as needed. That prevents a small web export from accidentally becoming your only copy.