Resize a whole batch of images

This is the decision that makes or breaks a batch resize, because the photos in a folder are rarely all the same shape.

Fit within gives a maximum box and scales each image under it while keeping its own proportions. A landscape photo and a portrait one both come out no larger than your limit, each still correctly shaped. It never enlarges, so small images are left alone. This is the safe default for a mixed folder.

Exact size forces every image to the same width and height. Perfect when you genuinely need uniform dimensions, like a grid of product thumbnails, but it will stretch any photo whose shape does not match. Use it only when all the images share a shape, or when uniform size matters more than proportion.

When in doubt, use Fit within. It is the one that cannot distort your pictures.