The map above shows Illinois and Indiana side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Illinois vs Indiana Geography
Land area: Illinois has a land area of 55,513 square miles (143,778 km²), while Indiana has 35,825 square miles (92,787 km²). Illinois' land area is 1.5 times (55%) larger than Indiana's.
Total area: Illinois: 57,913 square miles (149,995 km²) vs Indiana: 36,421 square miles (94,331 km²), including inland and coastal water. Illinois' total area is 1.6 times (59%) larger than Indiana's.
Length: Illinois is 390 miles (628 km) long from north to south; Indiana is 276 miles (444 km). Illinois' north-south length is 1.4 times (41%) longer than Indiana's.
Width: Illinois spans 283 miles (456 km) east to west; Indiana spans 193 miles (310 km). Illinois' east-west width is 1.5 times (47%) wider than Indiana's.
Highest point: Illinois's highest point is Charles Mound at 1,232 feet (376 m); Indiana's is Hoosier Hill at 1,255 feet (383 m). Hoosier Hill is 23 feet higher than Charles Mound.
Lowest point: Illinois's lowest point is Mississippi River at 292 feet; Indiana's is Ohio River at 330 feet. Illinois's lowest point is 38 feet lower.
Illinois vs Indiana Population and History
Population: Illinois has a population of 12,710,158 (2024), while Indiana has 6,924,275 (2024). Illinois' population is 1.8 times (84%) larger than Indiana's.
Population density: Illinois: 229.0 people per square mile vs Indiana: 193.3. Illinois' population density is 1.2 times (18%) higher than Indiana's.
Biggest city: Illinois's biggest city is Chicago with 2,721,308 people; Indiana's is Indianapolis with 891,484. Chicago's population is 3.1 times (205%) larger than Indianapolis'.
Largest metro area: Illinois's largest metropolitan area is Chicago-Naperville-Elgin, IL-IN metro area (9,408,576 people) vs Indiana's Chicago-Naperville-Elgin, IL-IN metro area (9,408,576). Chicago-Naperville-Elgin, IL-IN metro area and Chicago-Naperville-Elgin, IL-IN metro area have about the same population.
History: Illinois: Admitted to the Union on December 3, 1818, as the 21st state. Indiana: Admitted to the Union on December 11, 1816, as the 19th state. In its current form, Indiana is the older of the two by 2 years.
Illinois vs Indiana Economy
GDP: Illinois's GDP is $1,148.1 billion (2024) vs Indiana's $519.5 billion. Illinois' economic output is 2.2 times (121%) larger than Indiana's.
GDP per capita: Illinois: $90,330 per person vs Indiana: $75,028. Illinois' GDP per capita is 1.2 times (20%) higher than Indiana's.
Average income: Illinois: $74,522 vs Indiana: $64,077 average income per person (per capita personal income). Illinois' average income is 1.2 times (16%) higher than Indiana's.
Illinois vs Indiana Counties
Number of counties: Illinois has 102 counties, while Indiana has 92. Illinois' county count is 1.1 times (11%) higher than Indiana's.
Biggest county by area: Illinois's largest county is McLean County at 1,183 square miles; Indiana's is Allen County at 657 square miles. McLean County's land area is 1.8 times (80%) larger than Allen County's.
Smallest county by area: Illinois: Putnam County (160 sq mi) vs Indiana: Ohio County (86 sq mi). Putnam County's land area is 1.9 times (86%) larger than Ohio County's.
Most populous county: Illinois: Cook County (5,182,617 people) vs Indiana: Marion County (981,628 people). Cook County's population is 5.3 times (428%) larger than Marion County's.
Least populous county: Illinois: Hardin County (3,550 people) vs Indiana: Ohio County (5,996 people). Ohio County's population is 1.7 times (69%) larger than Hardin County's.
Richest county: Illinois: Cumberland County ($104,890 per capita income) vs Indiana: Hamilton County ($104,283). Cumberland County and Hamilton County have about the same income.
Poorest county: Illinois: Lawrence County ($43,606 per capita income) vs Indiana: Miami County ($44,940). Lawrence County and Miami County have about the same income.
Illinois vs Indiana Taxes
State income tax: Illinois has a top income tax rate of 4.95%, while Indiana has a top income tax rate of 2.95%. Illinois's top rate is 2 percentage points higher.
Property tax: Illinois: 1.92% effective rate vs Indiana: 0.74% of home value per year. Illinois's rate is 1.18 percentage points higher.
Sales tax: Illinois: 8.98% combined state and average local rate vs Indiana: 7%. Illinois's combined rate is 1.98 percentage points higher.
Official Websites
Illinois official website · Indiana official website
More Size Comparisons
All Illinois size comparisons · All Indiana 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.