Check the destination before choosing dimensions
Requirements can change and can differ between a post, cover, thumbnail, and profile image on the same platform. Consult the platform’s current help page or upload screen.
A square 1:1 image and a widescreen 16:9 image are different shapes. Pixel dimensions alone do not guarantee that a platform will show the whole image without cropping.
Crop to the shape, then resize
Move the crop area so that the important subject remains visible. Leave space around text and faces that may appear near the edge. Preview circular profile images in the destination when possible.
For an illustrative square output, crop to 1:1 before fitting within 1080×1080. These dimensions are an example, not a universal platform requirement. Smaller sources are not enlarged by default.
Check quality and file size after export
Choose a format the destination accepts and reduce quality only as much as necessary. Inspect text and detailed areas before downloading, then confirm the saved file meets the upload limit.
A platform may process the file again after upload. Check the published result rather than assuming that the downloaded version will be displayed unchanged. Keep the original for future sizes.