Sizes ASTM Grade Size Area of minimum Rectangle Minimum dimension of one side OOEE SPECIAL OOEE SPECIAL EE SPECIAL E SPECIAL A-1 (SPECIAL) NO. 1 NO. 2 NO. 3 NO. 4 NO. 5 NO. 5 1/2 NO. 6 Sq.In Equivalent Sq Cm 100 650 80 520 60 390 48 310 36 235 24 155 15 97 10 65 6 40 3 20 2 1/2 15 1 6.5 Inch Cm 4 10.0 4 10.0 4 10.0 4 10.0 3 1/2 8.8 3 8.8 2 5.0 2 5.0 1 1/2 3.8 1 2.5 7/8 2.2 3/4 1.9