Fit a landscape and portrait into a 1200-pixel box
Understand the fields
Maximum width and maximum height define the available box. They do not force the source into that shape. This matters for product photographs, documents and artwork where a stretched image would change the proportions of the subject.
Try a landscape
Choose a 3000 × 2000 source and enter 1200 for both limits. The width requires a factor of 0.4 and the height permits 0.6, so the tool uses 0.4. The output is 1200 × 800. The unused height is not added as a border.
Try a portrait
For a 2000 × 3000 source with the same limits, the height controls the fit. The result is 800 × 1200. This is expected behavior. To create an exact square with the whole image visible, use a canvas tool; to fill a square edge to edge, use a crop workflow.
Check the file
The download is PNG. Confirm the displayed dimensions and open the saved file in your image viewer. Existing transparency can remain transparent, but an opaque source remains opaque. PNG size is content dependent and can be larger than an efficiently encoded original JPEG.
Handle large requests
Requested edges must be no larger than 8192 pixels, and the requested box must stay within 32 megapixels. Source images have a separate 40-megapixel limit. Smaller requests use less memory and are often enough for a website image; large print dimensions should be chosen from the print requirement, not from a desire for the largest possible number.
Try and verify the workflow
A 3000 × 2000 image fitted inside a 1200 × 1200 box becomes 1200 × 800. The image stays in proportion; the box does not force a square crop.
Open proportional image resizer