It's about 0.0000000000000000000000000000000002 times as heavy as The Sun
In other words, 315 miligrams is 0.00000000000000000000000000000000016 times the weight of The Sun, and the weight of The Sun is 6,300,000,000,000,000,752,399,384,594,874,368.00000000000000000000000000000000000 times that amount.The sun has a mass of 1,999,999,999,999,999,879,418,332,743,206,357,172,224.000000000000000000000000000000000000000000 miligrams which represents 99.9% of the solar system's total mass. 98.7% of the sun's mass consists of hydrogen and helium — respectively the lightest and second-lightest elements in the universe.
It's about 0.00000000000000000000000000006 times as heavy as The Earth
In other words, 315 miligrams is 0.000000000000000000000000000052732 times the weight of The Earth, and the weight of The Earth is 18,963,999,999,999,998,786,336,194,560.000000000000000000000000000000000 times that amount.The mass of the planet Earth is 5,973,599,999,999,999,901,033,752,952,832.000000000000000000000000000000000000 miligrams. The element iron makes up about 32% of that mass, or 1,917,500,000,000,000,131,719,197,884,416.000000000000000000000000000000000000 miligrams.
It's about 0.00000000000006 times as heavy as The Great Pyramid of Giza
In other words, 315 miligrams is 0.000000000000053 times the weight of The Great Pyramid of Giza, and the weight of The Great Pyramid of Giza is 19,000,000,000,000 times that amount.(a.k.a. Pyramid of Khufu, a.k.a. Pyramid of Cheops) (Cairo, Egypt)
The Great Pyramid of Giza has an estimated mass of 5,900,000,000,000,000.000000000000000000 miligrams. The 2,300,000 stones used in the construction of the pyramid weighed an average 2,300,000,000 miligrams and were quarried from distances of up to 805 km (500 mi) away.
It's about 0.0000000000004 times as heavy as The Golden Gate Bridge
In other words, 315 miligrams is 0.000000000000391 times the weight of The Golden Gate Bridge, and the weight of The Golden Gate Bridge is 2,560,000,000,000 times that amount.(San Francisco, California and Marin County, California) (Post 1986 weight reduction; total weight of bridge, anchorage, and approaches)
Following the completion of the 1986 project to eliminate excess material, the total weight of the Golden Gate Bridge — including its anchorages and approaches — is 805,000,000,000,000.000000000000000000 miligrams. The two main cables in the spanning the bridge are spun out of a total of 129,000 km (80,200 mi) of wire.
It's about 0.0000000000010 times as heavy as The Empire State Building
In other words, 315 miligrams is 0.000000000000952 times the weight of The Empire State Building, and the weight of The Empire State Building is 1,050,000,000,000 times that amount.(New York City, New York)
The Empire State Building weighs approximately 331,000,000,000,000.000000000000000000 miligrams. About 4% of the building's weight is its 6,000 cu. m (200,000 cu. ft) of limestone façade.
It's about 0.000000000002 times as heavy as The Sears Tower
In other words, 315 miligrams is 0.000000000001561 times the weight of The Sears Tower, and the weight of The Sears Tower is 640,600,000,000 times that amount.(officially "Willis Tower" as of 2009) (Chicago, Illinois)
The Willis Tower weighs approximately 201,800,000,000,000.0000000000000000000 miligrams. The outer wall surface of the Tower is covered with black anodized aluminum panels which would total 110,000 sq. m (28 acres) if laid out together.
It's about 0.000000000003 times as heavy as The CN Tower
In other words, 315 miligrams is 0.0000000000026715 times the weight of The CN Tower, and the weight of The CN Tower is 374,320,000,000 times that amount.(a.k.a. La Tour CN, a.k.a. Canadian National Tower, a.k.a. Canada's National Tower) (Toronto, Canada)
The CN Tower weighs approximately 117,910,000,000,000.00000000000000000000 miligrams. The Tower is home to the world's highest glass floor — a viewing area that allows visitors to look straight down 342 m (1,120 ft) to the ground below.