Can someone please help me in calculating the total size in km of the Asteroid Belt? I have read the Asteroid Belt if lumped together would create a planet 4 times the size of Earth, however, I am trying to validate these numbers and am having difficulty in doing so. Here are the facts I have been able to locate: 7,000 known asteroids billions of estimated asteroids - sizes range from specs of dust to large hand sized objects the 4 largest were once considered planets and account for 1/2 the total mass of the Asteroid Belt - Ceres, with a diameter of 950 kilometers - Vesta has a diameter of 530 kilometers - Pallas has a diameter of 550 kilometers but is less massive than Vesta - Hygiea is 500 by 350 kilometers These 4 combine for a total diameter of 2,380 kilometers. If accounts for 1/2 the mass of the Asteroid Belt then when I add in the other 1/2 the total km would be 4,760 which is 1/4th the size of Earth's equatorial diameter (12,756 km). Which does not match to the original estimates where I have read the Asteroid Belt (combined) would be 4 times the size of Earth. Where am I miscalculating? Thanks.