Calculating the quantity/volume of concrete in the staircase is simple mathematics, in the given example 1 m width of the dog-legged staircase with two flights with a total rise of 3.3 m is considered. The riser is 0.15 m & Tread is 0.25 m whereas landing is assumed as of 1.0 m length.
Kindly refer attached image for calculation example.
STAIRCASE LOAD/CONCRETE QUANTITY CALCULATION