The map above shows Ontario and United Kingdom side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Ontario vs United Kingdom Geography
Land area: Ontario has a land area of 354,342 square miles (917,741 km²), while United Kingdom has 93,410 square miles (241,930 km²). Ontario's land area is 3.8 times (279%) larger than United Kingdom's.
Total area: Ontario: 415,598 square miles (1,076,395 km²) vs United Kingdom: 94,058 square miles (243,610 km²), including inland and coastal water. Ontario's total area is 4.4 times (342%) larger than United Kingdom's.
Length: Ontario is 1,085 miles (1,747 km) long from north to south; United Kingdom is 747 miles (1,202 km). Ontario's north-south length is 1.5 times (45%) longer than United Kingdom's.
Width: Ontario spans 1,013 miles (1,630 km) east to west; United Kingdom spans 429 miles (690 km). Ontario's east-west width is 2.4 times (136%) wider than United Kingdom's.
Highest point: Ontario's highest point is Ishpatina Ridge at 2,274 feet (693 m); United Kingdom's is Ben Nevis at 4,413 feet (1,345 m). Ben Nevis is 2,139 feet higher than Ishpatina Ridge.
Lowest point: Ontario's lowest point is Hudson Bay at 0 feet; United Kingdom's is The Fens (Holme Fen) at -10 feet. United Kingdom's lowest point is 10 feet lower.
Ontario vs United Kingdom Population and History
Population: Ontario has a population of 16,136,480 (2026), while United Kingdom has 69,487,000 (2025). United Kingdom's population is 4.3 times (331%) larger than Ontario's.
Population density: Ontario: 45.5 people per square mile vs United Kingdom: 743.9. United Kingdom's population density is 16.3 times higher than Ontario's.
Biggest city: Ontario's biggest city is Toronto with 2,794,356 people; United Kingdom's is London with 8,825,001. London's population is 3.2 times (216%) larger than Toronto's.
Largest metro area: Ontario's largest metropolitan area is Toronto CMA (6,202,225 people) vs United Kingdom's London (10,416,420). London's population is 1.7 times (68%) larger than Toronto CMA's.
History: Ontario: Joined Confederation on July 1, 1867, as one of the four founding provinces. 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 66 years.
Ontario vs United Kingdom Economy
GDP: Ontario's GDP is $873.9 billion (2024) vs United Kingdom's $4,002.6 billion. United Kingdom's economic output is 4.6 times (358%) larger than Ontario's.
GDP per capita: Ontario: $54,132 per person vs United Kingdom: $57,602. United Kingdom's GDP per capita is 1.1 times (6%) higher than Ontario's.
Official Websites
Ontario official website · United Kingdom official website
More Size Comparisons
All Ontario 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.