Question 1

Why 1080 × 1080?

Accepted Answer

It is the native resolution of a square social post: Instagram, Facebook and LinkedIn all render 1:1 images at 1080 px on the long edge, so uploading exactly that avoids both upscaling blur and a pointless re-encode on their side.

Question 2

My photo is not square — what happens?

Accepted Answer

With the aspect ratio locked, the image is fitted inside 1080 × 1080 without stretching, so the proportions survive. To truly fill the square, open the crop editor first, pick the Square ratio, and position the subject — then the resize lands exactly on 1080 × 1080.

Question 3

Can I also keep the file under a size limit?

Accepted Answer

Yes — turn on 'Maximum file size' and both requirements are applied together in one pass, which is usually what an ad platform's spec sheet asks for.

Question 4

Will resizing up make a small image sharper?

Accepted Answer

No. Enlarging invents pixels it does not have, so a 400 px photo scaled to 1080 will look soft. Start from the largest original you have; downscaling is where quality is preserved.