Integral calculus has a lot of practical applications. It can be used to find the area, surface area, Volume for all geometrical shapes.
Area= ∫ydx
Volume= ∫Πy2dx
Thus for finding area, volume and surface area Integral calculus can be used.
Also in various fields like Physics, Chemistry(Chemical kinetics), biotechnology and statistics integral calculus is used. Infact what addition and subtraction are for elementary students integral calculus is for XII and University students.
Thus Integral calculus is used everywhere.