Understanding the Paper Sizes: US-Letter Paper | A4 Paper | A3 Paper US-Letter Paper Size: 8.5 in x 11 in 7.5 in x 10 in 21.59 cm x 27.94 cm A4 Paper Size: 8.27 in x 11.69 in 7.27 in x 10.69 in 21 cm x 29.7 cm A3 Paper Size: 11.69 in x 16.54 in 10.69 in x 15.54 in 29.7 cm x 42 cm Comparison of US-Letter, A4, and A3 Paper Sizes - Images Below As you can see, all the papers above have a 1-inch difference between the paper sizes and the rectangular boxes. For example, the US-Letter Paper is 8.5 x 11 inches, and the rectangle is 7.5 x 10 inches, which means that the paper has a 0.5-inch margin. This allows you to place the pattern onto the template without losing the sizes of your e-pattern.