Preserve the original proportions
Keep the aspect ratio locked so the image does not stretch. Distortion is often more noticeable than mild compression.
Avoid unnecessary enlargement
Making an image larger requires the browser to create intermediate pixels. The result may be smoother, but it cannot contain the genuine detail of a higher-resolution original.
Use a suitable format
Keep PNG for transparent graphics and sharp interface elements. Use JPG or WebP for photographs, starting with a higher quality setting and lowering it only when a smaller file is needed.
Keep the original file
Download resized copies under new names and preserve the original. That gives you a clean source if you need another size later.
Resize your image
Open the free image resizer to apply these settings directly in your browser.