You can buy digital downloads at the sizes your photographer has made available. A digital download is simply a copy of the image file, sized in one of three ways.

A 1Mpix image is roughly 1 megapixel in size. In English, that means a square 1 megapixel image would be about 1000 pixels wide and 1000 pixels high. For comparison, the most common resolution for computer monitors is 1024x768. So a 1Mpix image is a bit larger than common monitor resolutions.

A 4Mpix image is 4 megapixels. This is a size that allows for quality printing at most reasonable sizes. If you want to print at really large poster sizes, you would probably want a larger image.

An Original image is the exact image that the photographer has put online. It is the original size of the image, identical in every way.

Note: Not all sizes are available for all images.