It's about one-one-thousandth as heavy as a Human Heart
In other words, 315 miligrams is 0.00 times the weight of a Human Heart, and the weight of a Human Heart is 1,000 times that amount.(human; adult)
The average human heart weighs about 310,000 miligrams. Each minute, the heart pumps between 10 and 20 liters (3 to 5 gallons) of blood through its chambers.
It's about 1,000 times as heavy as a Poppy Seed
In other words, 315 miligrams is 1,100 times the weight of a Poppy Seed, and the weight of a Poppy Seed is 0.0009 times that amount.(Papaver somniferum)
Fifty percent oil by weight, a poppy seed weighs approximately 0.3 mg. The true pigment of a poppy seed is brown in color, while the characteristic bluish color is an optical illusion caused by a layer of calcium oxalate crystals refracting light rays.
It's about one-one-thousandth as heavy as a Can of Soup
In other words, 315 miligrams is 0.001 times the weight of a Can of Soup, and the weight of a Can of Soup is 1,100 times that amount.(for Campbell''s Condensed Tomato Soup, 317.9 ml)
A can of Campbell''s Tomato Soup weighs 350,000 miligrams. Cans have been used to store soup and other foods since their invention in 1913, but a dedicated can opener was not developed until cans began to use thinner materials — prior to that time, cans were usually opened using various blunt instruments and tools.
It's about one-one-thousand-five-hundredth as heavy as a Football (American)
In other words, 315 miligrams is 0.000766296414767 times the weight of a Football (American), and the weight of a Football (American) is 1,304.978048611 times that amount.(a.k.a. "pigskin") (NFL standard)
Per National Football League official rules, an American football must weigh between 396,893.323750 miligrams and 425,242.8468750 miligrams. Because of NFL regulations, ceremonial considerations, and backup requirements, each NFL Superbowl requires the manufacture of 144 balls exclusively for the event.
It's about one-one-thousand-five-hundredth as heavy as a Football (Soccer)
In other words, 315 miligrams is 0.0007 times the weight of a Football (Soccer), and the weight of a Football (Soccer) is 1,400 times that amount.(a.k.a. Soccer, a.k.a. Association Football) (FIFA Law 2 specification)
According to FIFA's Law of the Game number 2, a football must weigh between 410,000 miligrams and 450,000 miligrams. An artifact on display at the Smith Art Gallery in Museum in Stirling, Scotland is said to be the world's oldest football and is about one-third to one-half the size of a modern football.
It's about one-two-thousandth as heavy as a Basketball
In other words, 315 miligrams is 0.0005050590006 times the weight of a Basketball, and the weight of a Basketball is 1,979.9666945 times that amount.(NBA official ball standards, Size 7)
A regulation NBA basketball, manufactured by Spalding, is known as a Size 7 ball and weighs 623,689.508750 miligrams. These balls have 4,118 pebbles each with a diameter of 2.5 mm
It's about one-three-thousandth as heavy as a liter of Water
In other words, 315 miligrams is 0.000314991 times the weight of a liter of Water, and the weight of a liter of Water is 3,174.692 times that amount.(fresh; 4° C / 39.2° F; maximum density)
Contrary to popular belief, 1 liter (0.0.264172052358148 gal) of water at 4° C / 39.2° F (its point of maximum density) weighs 1,000,028 miligrams rather than 1 kg exactly. The total volume of water on the planet Earth is about 13,590,000,000,000,000,000 (13.59 quntillion) L (3,590,000,000,000,000,000 gallons).