The calculated mass of the universe ranges anywhere from 1053 kg to 1060 kg. Since different methods were used, the disparity between the numbers is so great. No one actually knows what is out in the universe. Although many scientists would love to find an exact number, they have already started calculating how much it all weighs. Because no one knows an actual number, we can more likely agree that since the universe is still expanding, the mass is infinite.
mass of universe is zero because due big bang two type of energy produced one is positive energy and negative energy which also called dark matter or anti matter in big bang total no of negative energy equal to total no of positive energy and Einstein theory tells use mass is equal to energy before big bang every thing is zero big bang helps to crack the zero into negative and positive energy just like 0=-99+99, -99is negative energy and +99 is positive energy mass of universe is zero