The map above shows Illinois and Ontario side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Illinois vs Ontario Geography
Land area: Illinois has a land area of 55,513 square miles (143,778 km²), while Ontario has 354,342 square miles (917,741 km²). Ontario's land area is 6.4 times (538%) larger than Illinois'.
Total area: Illinois: 57,913 square miles (149,995 km²) vs Ontario: 415,598 square miles (1,076,395 km²), including inland and coastal water. Ontario's total area is 7.2 times (618%) larger than Illinois'.
Length: Illinois is 390 miles (628 km) long from north to south; Ontario is 1,085 miles (1,747 km). Ontario's north-south length is 2.8 times (178%) longer than Illinois'.
Width: Illinois spans 283 miles (456 km) east to west; Ontario spans 1,013 miles (1,630 km). Ontario's east-west width is 3.6 times (258%) wider than Illinois'.
Highest point: Illinois's highest point is Charles Mound at 1,232 feet (376 m); Ontario's is Ishpatina Ridge at 2,274 feet (693 m). Ishpatina Ridge is 1,042 feet higher than Charles Mound.
Lowest point: Illinois's lowest point is Mississippi River at 292 feet; Ontario's is Hudson Bay at 0 feet. Ontario's lowest point is 292 feet lower.
Illinois vs Ontario Population and History
Population: Illinois has a population of 12,710,158 (2024), while Ontario has 16,136,480 (2026). Ontario's population is 1.3 times (27%) larger than Illinois'.
Population density: Illinois: 229.0 people per square mile vs Ontario: 45.5. Illinois' population density is 5.0 times (403%) higher than Ontario's.
Biggest city: Illinois's biggest city is Chicago with 2,721,308 people; Ontario's is Toronto with 2,794,356. Chicago and Toronto have about the same population.
Largest metro area: Illinois's largest metropolitan area is Chicago-Naperville-Elgin, IL-IN metro area (9,408,576 people) vs Ontario's Toronto CMA (6,202,225). Chicago-Naperville-Elgin, IL-IN metro area's population is 1.5 times (52%) larger than Toronto CMA's.
History: Illinois: Admitted to the Union on December 3, 1818, as the 21st state. Ontario: Joined Confederation on July 1, 1867, as one of the four founding provinces. In its current form, Illinois is the older of the two by 49 years.
Illinois vs Ontario Economy
GDP: Illinois's GDP is $1,148.1 billion (2024) vs Ontario's $873.9 billion. Illinois' economic output is 1.3 times (31%) larger than Ontario's.
GDP per capita: Illinois: $90,330 per person vs Ontario: $54,132. Illinois' GDP per capita is 1.7 times (67%) higher than Ontario's.
Official Websites
Illinois official website · Ontario official website
More Size Comparisons
All Illinois size comparisons · All Ontario 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.