The map above shows Illinois and United Kingdom side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Illinois vs United Kingdom Geography
Land area
- Illinois has a land area of 55,513 square miles (143,778 km²), while United Kingdom has 93,410 square miles (241,930 km²).
- United Kingdom's land area is 1.7 times (68%) larger than Illinois'.
Total area
- Illinois: 57,913 square miles (149,995 km²) vs United Kingdom: 94,058 square miles (243,610 km²), including inland and coastal water.
- United Kingdom's total area is 1.6 times (62%) larger than Illinois'.
Length
- Illinois is 390 miles (628 km) long from north to south; United Kingdom is 747 miles (1,202 km).
- United Kingdom's north-south length is 1.9 times (92%) longer than Illinois'.
Width
- Illinois spans 283 miles (456 km) east to west; United Kingdom spans 429 miles (690 km).
- United Kingdom's east-west width is 1.5 times (52%) wider than Illinois'.
Highest point
- Illinois's highest point is Charles Mound at 1,232 feet (376 m); United Kingdom's is Ben Nevis at 4,413 feet (1,345 m).
- Ben Nevis is 3,181 feet higher than Charles Mound.
Lowest point
- Illinois's lowest point is Mississippi River at 292 feet; United Kingdom's is The Fens (Holme Fen) at -10 feet.
- United Kingdom's lowest point is 302 feet lower.
Illinois vs United Kingdom Population and History
Population
- Illinois has a population of 12,710,158 (2024), while United Kingdom has 69,487,000 (2025).
- United Kingdom's population is 5.5 times (447%) larger than Illinois'.
Population density
- Illinois: 229.0 people per square mile vs United Kingdom: 743.9.
- United Kingdom's population density is 3.2 times (225%) higher than Illinois'.
Biggest city
- Illinois's biggest city is Chicago with 2,721,308 people; United Kingdom's is London with 8,825,001.
- London's population is 3.2 times (224%) larger than Chicago's.
Largest metro area
- Illinois's largest metropolitan area is Chicago-Naperville-Elgin, IL-IN metro area (9,408,576 people) vs United Kingdom's London (10,416,420).
- London's population is 1.1 times (11%) larger than Chicago-Naperville-Elgin, IL-IN metro area's.
History
- Illinois: Admitted to the Union on December 3, 1818, as the 21st state.
- United Kingdom: Formed as the United Kingdom of Great Britain and Ireland on January 1, 1801; took its current form in 1922.
- In its current form, United Kingdom is the older of the two by 17 years.
Illinois vs United Kingdom Economy
GDP
- Illinois's GDP is $1,148.1 billion (2024) vs United Kingdom's $4,002.6 billion.
- United Kingdom's economic output is 3.5 times (249%) larger than Illinois'.
GDP per capita
- Illinois: $90,330 per person vs United Kingdom: $57,602.
- Illinois' GDP per capita is 1.6 times (57%) higher than United Kingdom's.
Average income
- Illinois: $74,522 vs United Kingdom: $54,550 average income per person (per capita personal income).
- Illinois' average income is 1.4 times (37%) higher than United Kingdom's.
Official Websites
Illinois official website · United Kingdom official website
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More Size Comparisons
All Illinois size comparisons · All United Kingdom 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.