The map above shows Idaho and Kentucky side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Idaho vs Kentucky Geography
Land area: Idaho has a land area of 82,645 square miles (214,051 km²), while Kentucky has 39,485 square miles (102,267 km²). Idaho's land area is 2.1 times (109%) larger than Kentucky's.
Total area: Idaho: 83,569 square miles (216,441 km²) vs Kentucky: 40,406 square miles (104,651 km²), including inland and coastal water. Idaho's total area is 2.1 times (107%) larger than Kentucky's.
Length: Idaho is 483 miles (778 km) long from north to south; Kentucky is 257 miles (414 km). Idaho's north-south length is 1.9 times (88%) longer than Kentucky's.
Width: Idaho spans 352 miles (566 km) east to west; Kentucky spans 418 miles (672 km). Kentucky's east-west width is 1.2 times (19%) wider than Idaho's.
Highest point: Idaho's highest point is Borah Peak at 12,631 feet (3,850 m); Kentucky's is Black Mountain at 4,134 feet (1,260 m). Borah Peak is 8,497 feet higher than Black Mountain.
Lowest point: Idaho's lowest point is Snake River at 718 feet; Kentucky's is Mississippi River at 270 feet. Kentucky's lowest point is 448 feet lower.
Idaho vs Kentucky Population and History
Population: Idaho has a population of 2,001,619 (2024), while Kentucky has 4,588,372 (2024). Kentucky's population is 2.3 times (129%) larger than Idaho's.
Population density: Idaho: 24.2 people per square mile vs Kentucky: 116.2. Kentucky's population density is 4.8 times (380%) higher than Idaho's.
Biggest city: Idaho's biggest city is Boise with 237,963 people; Kentucky's is Louisville with 640,796. Louisville's population is 2.7 times (169%) larger than Boise's.
Largest metro area: Idaho's largest metropolitan area is Boise City, ID metro area (845,877 people) vs Kentucky's Cincinnati, OH-KY-IN metro area (2,302,815). Cincinnati, OH-KY-IN metro area's population is 2.7 times (172%) larger than Boise City, ID metro area's.
History: Idaho: Admitted to the Union on July 3, 1890, as the 43rd state. Kentucky: Admitted to the Union on June 1, 1792, as the 15th state. In its current form, Kentucky is the older of the two by 98 years.
Idaho vs Kentucky Economy
GDP: Idaho's GDP is $129.0 billion (2024) vs Kentucky's $295.4 billion. Kentucky's economic output is 2.3 times (129%) larger than Idaho's.
GDP per capita: Idaho: $64,457 per person vs Kentucky: $64,375. Idaho and Kentucky have about the same GDP per capita.
Average income: Idaho: $62,323 vs Kentucky: $58,256 average income per person (per capita personal income). Idaho's average income is 1.1 times (7%) higher than Kentucky's.
Idaho vs Kentucky Counties
Number of counties: Idaho has 44 counties, while Kentucky has 120. Kentucky's county count is 2.7 times (173%) higher than Idaho's.
Biggest county by area: Idaho's largest county is Idaho County at 8,478 square miles; Kentucky's is Pike County at 786 square miles. Idaho County's land area is 10.8 times larger than Pike County's.
Smallest county by area: Idaho: Payette County (407 sq mi) vs Kentucky: Gallatin County (98 sq mi). Payette County's land area is 4.1 times (314%) larger than Gallatin County's.
Most populous county: Idaho: Ada County (535,799 people) vs Kentucky: Jefferson County (793,881 people). Jefferson County's population is 1.5 times (48%) larger than Ada County's.
Least populous county: Idaho: Clark County (794 people) vs Kentucky: Robertson County (2,382 people). Robertson County's population is 3.0 times (200%) larger than Clark County's.
Richest county: Idaho: Blaine County ($202,612 per capita income) vs Kentucky: Oldham County ($87,137). Blaine County's income is 2.3 times (133%) richer than Oldham County's.
Poorest county: Idaho: Madison County ($29,485 per capita income) vs Kentucky: Elliott County ($31,817). Elliott County's income is 1.1 times (8%) richer than Madison County's.
Idaho vs Kentucky Taxes
State income tax: Idaho has a top income tax rate of 5.3%, while Kentucky has a top income tax rate of 3.5%. Idaho's top rate is 1.8 percentage points higher.
Property tax: Idaho: 0.43% effective rate vs Kentucky: 0.71% of home value per year. Kentucky's rate is 0.28 percentage points higher.
Sales tax: Idaho: 6.03% combined state and average local rate vs Kentucky: 6%. Idaho's combined rate is 0.03 percentage points higher.
Official Websites
Idaho official website · Kentucky official website
More Size Comparisons
All Idaho size comparisons · All Kentucky 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.