For high-definition photos at 250 kilobytes of memory each, a 1-gigabyte memory card holds 4,000 pictures. HD wallpaper images are about 250 kilobytes; personal pictures are smaller and require less memory. Super-HD images of 2,560 by 1,600 pixels are up to 1.6 megabytes. A 1-gigabyte card holds 625 such photos.
Most pictures are saved in Joint Photographic Experts Group, or "JPEG," format, where the percentage of loss during photo compression also factors into the resulting photo size.
There are many online photo file converters that reduce the size of a photo via compression, allowing more pictures to fit on a 1-gigabyte memory card. The original size of the image is restored later without any loss of data.