County outline
Where Hardin County is located
Area breakdown
Land accounts for 99.9% of Hardin County’s measured area and water for 0.1%. Its combined area converts to 1,218.7 square kilometers or approximately 301,138 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 470.285 | 1,218.033 | 300,982.4 |
| Water | 0.243 | 0.629 | 155.5 |
| Total | 470.528 | 1,218.662 | 301,137.9 |
How Hardin County compares
By original Census land area, Hardin County ranks #32 of 88 in Ohio and #2191 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.079 times the Ohio county-equivalent median of 436 square miles. It accounts for 1.2% of the combined county land area in the state.
See the complete Ohio ranking · What counts as a county equivalent?
Population and density of Hardin County
The Census Bureau estimates that 30,072 people lived in Hardin County on July 1, 2025. That ranks #1,481 of 3,222 county equivalents nationally and #72 of 88 in Ohio. Since the April 1, 2020 estimates base of 30,691, the population has declined by 619 (−2%), compared with +0.9% for Ohio as a whole.
With 470.3 square miles of land, that is 64 people per square mile (25 per km²), placing Hardin County #1,337 nationally for density and #77 in Ohio. The median county equivalent has 47 people per square mile; the Ohio median is 120. Put another way, there are about 10 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 30,724 | 30,417 | 30,367 | 30,411 | 30,254 | 30,072 |
| Change | — | −307 | −50 | +44 | −157 | −182 |
U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.
Cities and towns in Hardin County
9 incorporated places lie at least partly in Hardin County. Together they are home to 17,084 people (56.8%); the other 12,988 (43.2%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Kenton city, with 7,808 residents in the county.
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Kenton cityCounty seat | 7,808 | −1.8% | 4.993 |
| Ada village | 4,985 | −6.4% | 2.131 |
| Forest village | 1,332 | −1.6% | 1.672 |
| Alger village | 827 | −1.8% | 0.296 |
| Dunkirk village | 753 | −2.3% | 0.658 |
| Mount Victory village | 595 | −1.5% | 0.843 |
| McGuffey village | 454 | −1.9% | 0.372 |
| Ridgeway villageAlso in 1 other county | 202 | −2.4% | 0.566 |
| Patterson village | 128 | −1.5% | 0.088 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Hardin County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Hardin County is not part of any metropolitan or micropolitan statistical area in the Office of Management and Budget’s July 2023 delineation; 1,306 other county equivalents are also outside one. These areas are built around an urban core of at least 10,000 people plus the counties tied to it by commuting, so counties outside them are generally rural.
ZIP codes
16 ZIP Code Tabulation Areas have land in Hardin County; 9 of them have most of their land inside the county, and the others mainly cover neighboring areas.
43310433264333143332433404334543346433474581045812458354583645843458504585945896
ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.
Counties bordering Hardin County
Hardin County shares a land border with 7 county equivalents. It has more land than 6 of them. The largest neighbor is Hancock County (531.3 mi²) and the smallest is Auglaize County (401.4 mi²). Together with its neighbors, Hardin County forms a block of 3,506.4 mi² of land, of which it holds 13.4%.
| Bordering county equivalent | Land mi² | Size vs. Hardin | Compare |
|---|---|---|---|
| Hancock County | 531.3 | 1.1× larger | Compare |
| Logan County | 458.5 | about the same | Compare |
| Union County | 431.7 | 1.1× smaller | Compare |
| Wyandot County | 406.9 | 1.2× smaller | Compare |
| Marion County | 403.8 | 1.2× smaller | Compare |
| Allen County | 402.5 | 1.2× smaller | Compare |
| Auglaize County | 401.4 | 1.2× smaller | Compare |
How big is Hardin County compared with U.S. states?
Hardin County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2.2 times as much. Ohio’s county land could hold about 87 areas the size of Hardin County.
Another way to picture it: the same land area would fill a square about 21.7 miles (34.9 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.
State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.
What stands out about Hardin County?
Hardin County has more land than 1,031 of the other 3,221 county equivalents in the dataset.
A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.
Does including water change its rank?
Using land plus water places Hardin County at #2,278 nationally by total area, 87 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.
Its water share is 0.1%, compared with a national county-equivalent median of 1.2% — 1.1 percentage points lower. This describes the statistical geography’s land/water mix, not flood exposure or developable land.
Closest positions in the national land ranking
These entries sit immediately beside Hardin County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2190 | Nelson County, Virginia | 470.7 | Compare |
| #2191 | Hardin County, Ohio | 470.3 | This county |
| #2192 | Ralls County, Missouri | 469.8 | Compare |
Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.
Representative coordinates
The Census internal point is 40.660415, -83.664077. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.
Source and precision
U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 1,218,033,110 m²; AWATER: 630,279 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.
Common questions
How big is Hardin County?
Hardin County, Ohio has 470.3 square miles (1,218 km²) of land and 0.243 square miles of water, for a total area of 470.5 square miles. It ranks #2191 of 3,222 U.S. county equivalents by land area.
Is Hardin County the largest county in Ohio?
No. Hardin County ranks #32 of 88 in Ohio by land area. The largest is Ashtabula County, with 702.4 square miles of land.
What counties border Hardin County?
Hardin County shares a land border with Hancock County, Logan County, Marion County, Wyandot County, Allen County, Auglaize County, and Union County.
What is the population of Hardin County?
The Census Bureau estimates Hardin County had 30,072 residents on July 1, 2025, ranking #1,481 of 3,222 county equivalents. That is 64 people per square mile of land.
What is the county seat of Hardin County?
The county seat of Hardin County is Kenton.
What cities and towns are in Hardin County?
Hardin County has 9 incorporated places. The most populous five are Kenton city, Ada village, Forest village, Alger village, and Dunkirk village; 12,988 residents live outside any incorporated place.
Is Hardin County part of a metropolitan area?
No. Hardin County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.
How many ZIP codes are in Hardin County?
16 ZIP Code Tabulation Areas have land in Hardin County, and 9 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Hardin County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 2.2 times as much land.
How many acres of land are in Hardin County?
The land measurement converts to approximately 300,982 acres. Including water, total area is approximately 301,138 acres. One square mile equals 640 acres.
Why might another source show a different area?
Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.
Can this establish a property boundary?
No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.