A measure of the fineness of an aggregate; a factor obtained by adding the total percentages of an aggregate sample retained on each of the following sieves and dividing the sum by 100: No. 100 (150 ¼m), No. 50 (300 ¼m), No. 30 (600 ¼m), No. 16 (1.18 mm), No. 8 (2.36 mm), No. 4 (4.75 mm), 3 €8 inch (9.5 mm), 3 €4 inch (19.0 mm), 11 €2 inch (38.1 mm).