Aspect ratio is the term used to describe the dimensions of an image by comparing the width to the height. Here are a few common ratios for common frame sizes.
3:4 = 3x4, 6x8, 9x12, 12x16, 18x24, 30x40, 36x48
5:7 = 5x7, 10x14, 20x28
4:5 = 8x10, 16x20, 24 x 30
11x14 = Use file 4:5 ratio for this size.
1 to 1 = 6x6, 10x10, 12x12
2:3 = 6x9, 12x18, 16x24, 20x30, 24x36