The print dimensions listed are for the size of paper it is printed on including the white border. All frames and mattes adds to the sizing.
Size example 1: On a 10x10" print the printed area is 7x7" which leaves a 1.5" white border.
Size example 2: On a 10x10" print with a matte, the matte will have outside dimensions of 13x13".
Size example 3: On a 16x16" print with a matte and frame, the frame will have outside dimensions of 20x20".