Image size is dictated by the images horizontal and vertical resolution and bits per pixel. For example - a standard color video image is 640 pixels horizontal by 480 pixels vertical by 24 bits per pixel. Since we're concerned with how many bytes an image consumes on the hard drive we need to convert the 24 bits to bytes (24/8 = 3 bytes). The formula is - 640 * 480 * 3 = 921,600 bytes or 921Kb for an uncompressed image file. The same applies to monochrome images, however, since monochrome video images are only 8 bits the formula is - 640 * 480 * 1 = 307,200 bytes or 307 Kb.

High bit depth, monochrome images, 10, 12, and 16 bits/pixel all default to 16 bits/pixel when they are saved as TIFF files. The formula is - 640 * 480 * 2 = 614,400 bytes.