The map above shows Illinois and South Australia side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Illinois vs South Australia Geography
Land area: Illinois has a land area of 55,513 square miles (143,778 km²), while South Australia has 380,048 square miles (984,321 km²). South Australia's land area is 6.8 times (585%) larger than Illinois'.
Total area: Illinois: 57,913 square miles (149,995 km²) vs South Australia: 380,048 square miles (984,321 km²), including inland and coastal water. South Australia's total area is 6.6 times (556%) larger than Illinois'.
Length: Illinois is 390 miles (628 km) long from north to south; South Australia is 1,078 miles (1,735 km). South Australia's north-south length is 2.8 times (176%) longer than Illinois'.
Width: Illinois spans 283 miles (456 km) east to west; South Australia spans 825 miles (1,328 km). South Australia's east-west width is 2.9 times (192%) wider than Illinois'.
Highest point: Illinois's highest point is Charles Mound at 1,232 feet (376 m); South Australia's is Mount Woodroffe at 4,708 feet (1,435 m). Mount Woodroffe is 3,476 feet higher than Charles Mound.
Lowest point: Illinois's lowest point is Mississippi River at 292 feet; South Australia's is Lake Eyre at -49 feet. South Australia's lowest point is 341 feet lower.
Illinois vs South Australia Population and History
Population: Illinois has a population of 12,710,158 (2024), while South Australia has 1,908,182 (2025). Illinois' population is 6.7 times (566%) larger than South Australia's.
Population density: Illinois: 229.0 people per square mile vs South Australia: 5.0. Illinois' population density is 45.8 times higher than South Australia's.
Largest metro area: Illinois's largest metropolitan area is Chicago-Naperville-Elgin, IL-IN metro area (9,408,576 people) vs South Australia's Greater Adelaide (1,491,015). Chicago-Naperville-Elgin, IL-IN metro area's population is 6.3 times (531%) larger than Greater Adelaide's.
History: Illinois: Admitted to the Union on December 3, 1818, as the 21st state. South Australia: Became an Australian state at Federation on January 1, 1901; founded as a colony in 1836. In its current form, Illinois is the older of the two by 83 years.
Illinois vs South Australia Economy
GDP: Illinois's GDP is $1,148.1 billion (2024) vs South Australia's $100.2 billion. Illinois' economic output is 11.5 times larger than South Australia's.
GDP per capita: Illinois: $90,330 per person vs South Australia: $52,511. Illinois' GDP per capita is 1.7 times (72%) higher than South Australia's.
Official Websites
Illinois official website · South Australia official website
More Size Comparisons
All Illinois size comparisons · All South Australia size comparisons
Area, elevation and boundary figures come from official national statistics and US Census Bureau and Natural Earth boundary data; US state population, economic, county and tax figures come from the US Census Bureau, the Bureau of Economic Analysis and the Tax Foundation. Figures are rounded and for general reference.