Set dimensions without stretching
Aspect ratio is width divided by height. Lock the ratio so changing one dimension updates the other proportionally. If the target frame has a different shape, crop the image deliberately rather than stretching it. GZ's online image resizer accepts pixel dimensions or a percentage scale and previews the new width and height.
Resize to the largest required use, with enough pixels for the actual display density. Avoid enlarging a small source expecting it to gain detail; interpolation makes more pixels, not more source information. Resizing cannot restore detail that was not present in the original.
Choose a useful output
After resizing, pick a format that suits the content and compare file size. Quality controls affect lossy formats such as JPEG or lossy WebP; PNG canvas export ignores the quality slider.
Keep the original and name derivatives with their intended use or dimensions so you can replace them if the layout changes.
Frequently asked questions
Can I resize without changing quality?
Changing pixel dimensions resamples pixels. A smaller derivative can look the same at its intended display size, but the pixel data has changed.