It's about one-fiftieth as heavy as a Battery (AA).
In other words, the weight of a Battery (AA) is 50 times 491 miligrams.(Alkaline)
An "AA" size battery weighs 24,000 miligrams. AA batteries came into common use during World War II and were given their name by the American National Standards Institute (ANSI) Committee C18 because they were smaller than the "A" size batteries which were invented first.
It's about one-seventieth as heavy as a Light Bulb.
In other words, the weight of a Light Bulb is 71 times 491 miligrams.(a.k.a. lamp) (for A19-size, 60w, incandescent bulb by Bulbrite; package weight)
A standard, sixty-watt light bulb weighs about 34,000 miligrams. The tightly-coiled filament inside a bulb of this size would measure about 579mm if uncoiled and stretched out.
It's about one-ninety-fifth as heavy as a Golf Ball.
In other words, 491 miligrams is 0.01069 times the weight of a Golf Ball, and the weight of a Golf Ball is 93.55 times that amount.(per R&A USGA Rules of Golf; maximum rule weight)
According to the Rules of Golf (as approved by the United States Golf Association and the Rules Committee of the Royal and Ancient Golf Club of Saint Andrews), golf balls must weigh no more than 45,930 miligrams. Golf balls are not required to have the familiar dimpled pattern, but the design has been popular since its invention in 1905 because it reduces drag while increasing lift.
It's about 100 times as heavy as a Grain of Sand.
In other words, 491 miligrams is 110 times the weight of a Grain of Sand, and the weight of a Grain of Sand is 0.0091 times that amount.(medium grain)
With tremendous variety in the size of grain and the component material, grains of sand weigh an average of 4.4 mg. In 2007, a team of seven in Myrtle Beach created the world's tallest sandcastle, which measured 15.10 m (49.55 ft) in height.
It's about one-one-hundredth as heavy as a Tennis Ball.
In other words, 491 miligrams is 0.00851 times the weight of a Tennis Ball, and the weight of a Tennis Ball is 118 times that amount.(ITF Standard; for Type 2 ball)
Per International Tennis Federation standard, regulation tennis balls must weigh about 57,700 miligrams. Competition balls are also tested for bounce height, with the standards requiring that a ball dropped from 254 cm must bounce back to a height of 135 cm to 147 cm.
It's about one-one-hundred-fiftieth as heavy as a Battery (C).
In other words, the weight of a Battery (C) is 130 times 491 miligrams.(Alkaline)
A "C" size battery weighs 65,000 miligrams. C batteries are typically used in medium-drain devices such as musical instruments.
It's about 150 times as heavy as a Sesame Seed.
In other words, 491 miligrams is 135 times the weight of a Sesame Seed, and the weight of a Sesame Seed is 0.00741 times that amount.(Sesamum indicum)
A sesame seed weighs approximately 3.64 mg. The McDonald's Big Mac sandwich, which is well-known for its sesame seed top bun, accounts for the consumption of an estimated 2,010,000,000 miligrams of sesame seeds each day.