It's about 7,000,000 times as big as Bill Gates' Home.
In other words, 31,000,000 dunams is 6,929,000 times the size of Bill Gates' Home, and the size of Bill Gates' Home is 0.00000014430 times that amount.(Medina, Washington)
One of the largest homes in the world, Bill and Melinda Gates' home has a total area of 4.4740 dunams, including 7 bedrooms, 24 bathrooms, 6 kitchens, 6 fireplaces, a 0.230 dunams gym, a 0.09 dunams dining room, and a 0.190 dunams library. It was designed by Bohlin Cywinski Jackson, the same architectural firm responsible for the design of one of Apple Inc's flagship stores on Fifth Avenue in New York City.
It's about 20,000,000 times as big as a Hockey rink.
In other words, 31,000,000 dunams is 20,437,376.50 times the size of a Hockey rink, and the size of a Hockey rink is 0.00000004892995930 times that amount.(per NHL specification)
Per National Hockey League Official Rules, a hockey rink should measure 60.96 m long by 25.908 m wide with a corner arc radius of 8.5344 m, for a total area of about 1.516828740 dunams. Ice hockey is believed to have developed from field hockey after players began holding games on ice rinks, which had been traditionally used for the sport of curling.
It's about 25,000,000 times as big as Fort Knox.
In other words, 31,000,000 dunams is 26,300,000 times the size of Fort Knox, and the size of Fort Knox is 0.0000000380 times that amount.(a.k.a. the United States Bullion Depository, a.k.a. "Gold Vault") (Kentucky)
The United States Bullion Depository, commonly referred to by the metonym "Fort Knox" (in spite of the fact that the Depository is not located on the Fort proper), measures 32.0 m (105 ft) by 36.9 m (121 ft), for a total area of about 1.180 dunams. The Depository is most famous for housing the largest portion of the national gold reserve, but has also temporarily housed the original US Declaration of Independence, an original copy of the US Constitution, and other important documents, kept there for safe keeping during World War II.
It's about 65,000,000 times as big as a Basketball court.
In other words, 31,000,000 dunams is 62,545,683.770 times the size of a Basketball court, and the size of a Basketball court is 0.00000001598831350 times that amount.(per NBA regulation)
Per NBA rules , a basketball court should measure 29.5656 m long by 16.764 m wide, for a total area of 0.49563771840 dunams. The first basketball game, held in a Springfield Massachusetts YMCA, was played on a court half the size of today's NBA standard and ended with a score of 1-0.
It's about 90,000,000 times as big as an IMAX screen.
In other words, 31,000,000 dunams is 87,520,000 times the size of an IMAX screen, and the size of an IMAX screen is 0.000000011430 times that amount.(standard)
An IMAX movie theater screen measures 22 m (72 ft) by 16 m (52 ft) for a total area of 0.35420 dunams. Because the film used in an IMAX movie is more than eight times larger than regular film, the platters of a two-and-a-half hour feature film can weigh up to 250 kg (550 lbs).
It's about 100,000,000 times as big as a Tennis court.
In other words, 31,000,000 dunams is 118,832,340 times the size of a Tennis court, and the size of a Tennis court is 0.00000000841521760 times that amount.(per ITF specification; for doubles)
Per International Tennis Federation Rules of Tennis 2009, a doubles tennis court should measure 23.7744 m long by 10.9728 m, for a total area of about 0.260760 dunams. Courts may be surfaced with crushed red stone, shale, brick, hard-soil grass, or asphalt.
It's about 2,000,000,000 times as big as a Parking Space.
In other words, 31,000,000 dunams is 2,070,000,000 times the size of a Parking Space, and the size of a Parking Space is 0.0000000004830 times that amount.(a.k.a Parking Stall) (average; surface lot; North America)
An average-size parking space in a North American surface lot measures 0.015 dunams. Due to the high real estate prices at the time, parking spaces in a densely-populated part of Manhattan would sell for an average of $165,000 in 2007, with some spaces fetching up to $225,000.