The Fineness modulus FM is an empirical figure obtained by adding the total percentage of the sample of an aggregate retained on each of a specified series of sieves and dividing the sum by 100 The sieve sizes are 0 15 mm 0 3 mm 0 6 mm 1 18 mm 2 36 mm 4 75 mm 9 5 mm 19 0 mm 38 1 mm and larger increasing in the ratio of 2 1