It's about one-and-one-tenth times as big as Tshwane
In other words, 644,718 hectares is 1.012 times the size of Tshwane, and the size of Tshwane is 0.98810 times that amount.(a.k.a. Pretoria, a.k.a. ePitoli, a.k.a. Jacaranda City) (Gauteng, South Africa) (for Tshwane metro area)
Tshwane, South Africa's executive capital, measures 636,800 hectares in total metro area. The Reserve Bank of South Africa is the city's tallest building at 150 m in height.
It's about as big as Ottawa
In other words, the size of Ottawa is 1.04967 times 644,718 hectares.(a.k.a. Ville d'Ottawa) (Ottawa metropolitan area) (Canada)
The capital and fourth-largest city of Canada, Ottawa measures 676,741 hectares. For many years, the skyline of Ottawa was dominated by the Peace Tower (la Tour de la Paix), with city ordinances preventing other structures from exceeding its 92.2 m height.
It's about one-and-one-tenth times as big as Prince Edward Island
In other words, 644,718 hectares is 1.134290 times the size of Prince Edward Island, and the size of Prince Edward Island is 0.8816090 times that amount.(a.k.a. PEI, a.k.a. P.E.I., a.k.a. Île-du-Prince-Édouard, a.k.a. Eilean a' Phrionnsa, a.k.a. Garden of the Gulf, a.k.a. Birthplace of the Confederation, a.k.a. Île Saint-Jean)
Prince Edward Island, located off Canada's eastern coast in the Gulf of St. Lawrence, measures 568,391 hectares in total area. Significant among Prince Edward Island's industries is agriculture, with the island producing 1.3 billion kg (1.4 million tons) of potatoes each year — almost 21% the output of the US state of Idaho with 3% as much land.
It's about one-and-one-fourth times as big as Calgary
In other words, 644,718 hectares is 1.261630 times the size of Calgary, and the size of Calgary is 0.7926250 times that amount.(Calgary metro) (Canada)
One of the largest cities in Canada, Calgary measures 511,021 hectares. Calgary has a large parks system, with 800 km of pathways connecting the city's various parks.
It's about one-and-three-tenths times as big as Grand Canyon National Park
In other words, 644,718 hectares is 1.30758770 times the size of Grand Canyon National Park, and the size of Grand Canyon National Park is 0.7647670590 times that amount.(Coconino County and Mohave Counties, Arizona, near Fredonia and Grand Canyon, Arizona)
Containing the 446 km (277 mi) Grand Canyon gorge, Grand Canyon National Park covers 493,059 hectares.
It's about one-and-two-fifths times as big as Fort Bliss
In other words, 644,718 hectares is 1.420 times the size of Fort Bliss, and the size of Fort Bliss is 0.7040 times that amount.(near Las Cruces, New Mexico and El Paso, Texas)
Fort Bliss is the United States Army's second-largest installation with a total area of 453,000 hectares. It is known as the largest TRADOC (Training and Doctrine Command) site, the Army's largest maneuver area, and the country's largest contiguous tract of open airspace.
It's about one-and-a-half times as big as Kangaroo Island
In other words, 644,718 hectares is 1.4640 times the size of Kangaroo Island, and the size of Kangaroo Island is 0.68310 times that amount.(a.k.a. Karta) (state of South Australia, Australia)
Kangaroo Island, off the southern coast of Australia, measures 440,500 hectares in total area. The island is famous for its ligurian bee colonies, exporting over 100 tonnes of honey each year.