4) calculation of cement quantity. 5) calculation of sand quantity. how to calculate dry volume of mortar 1:4 given data:assume volume of mortar 1m3. density of cement 1440 kgm3. cement in 1 bag 50 kg. 1m3 35.3147 cubic feet. mix ratio is 1:4 ( one part is cement and 4 part is sand) total proportion 14 5. part of cement 15.