It's about one-eight-hundred-thousandth as heavy as a Golf Ball
In other words, 0.000903 grains is 0.0000012740 times the weight of a Golf Ball, and the weight of a Golf Ball is 784,900 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 708.80 grains. 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 one-one-millionth as heavy as a Tennis Ball
In other words, 0.000903 grains is 0.000001010 times the weight of a Tennis Ball, and the weight of a Tennis Ball is 990,000 times that amount.(ITF Standard; for Type 2 ball)
Per International Tennis Federation standard, regulation tennis balls must weigh about 890 grains. 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 0.0000009 times as heavy as a Battery (C)
In other words, 0.000903 grains is 0.000000900 times the weight of a Battery (C), and the weight of a Battery (C) is 1,100,000 times that amount.(Alkaline)
A "C" size battery weighs 1,000 grains. C batteries are typically used in medium-drain devices such as musical instruments.
It's about 0.0000006 times as heavy as a Deck of Cards
In other words, 0.000903 grains is 0.000000620 times the weight of a Deck of Cards, and the weight of a Deck of Cards is 1,600,000 times that amount.(ISO 216 B8 size, a.k.a. "poker size" 63 x 88 mm, 52-card deck)
A deck of 52 ISO 216 B8-size playing cards weighs 1,500 grains. Utilizing nearly 3,700 decks, the record-holding largest card tower was built in early 2010, stood over 3.5 m (11 ft), and weighed over 3,500,000 grains.
It's about 0.0000005 times as heavy as a Battery (D)
In other words, 0.000903 grains is 0.0000004330 times the weight of a Battery (D), and the weight of a Battery (D) is 2,310,000 times that amount.(Alkaline)
A "D" size battery weighs 2,080 grains. The D size battery is the oldest of the modern battery sizes, first invented by the National Carbon Company in 1898.
It's about 0.0000004 times as heavy as a Baseball
In other words, 0.000903 grains is 0.000000402731707317070 times the weight of a Baseball, and the weight of a Baseball is 2,483,042.63565890 times that amount.(MLB rules)
Per Major League Baseball rules, a baseball must weigh between 2,187.50 grains and 2,296.8750 grains. A major league pitcher can throw a baseball at up to 150 kph (91 mph) (with a fastball pitch), with record-setting pitches as fast as 171 kph (106 mph).
It's about 0.0000004 times as heavy as a Billiard Ball
In other words, 0.000903 grains is 0.000000358956521739130 times the weight of a Billiard Ball, and the weight of a Billiard Ball is 2,785,852.71317830 times that amount.(American-style, WPA specifications)
Per the World Pool-Billiard Association, a billiard ball weight must weigh between 2,406.250 grains and 2,625 grains. According to legend, the difficulty in obtaining elephant ivory for the manufacture of billiard balls in the 19th century inspired the search for a replacement material, which led to the development of the first industrial plastic.