County outline
Where Champaign County is located
Area breakdown
Land accounts for 99.8% of Champaign County’s measured area and water for 0.2%. Its combined area converts to 1,113.2 square kilometers or approximately 275,084 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 428.977 | 1,111.045 | 274,545.3 |
| Water | 0.842 | 2.181 | 538.9 |
| Total | 429.819 | 1,113.226 | 275,084.2 |
How Champaign County compares
By original Census land area, Champaign County ranks #47 of 88 in Ohio and #2370 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.984 times the Ohio county-equivalent median of 436 square miles. It accounts for 1% of the combined county land area in the state.
See the complete Ohio ranking · What counts as a county equivalent?
Population and density of Champaign County
The Census Bureau estimates that 38,820 people lived in Champaign County on July 1, 2025. That ranks #1,236 of 3,222 county equivalents nationally and #63 of 88 in Ohio. Since the April 1, 2020 estimates base of 38,711, the population has grown by 109 (+0.3%), compared with +0.9% for Ohio as a whole.
With 429 square miles of land, that is 90 people per square mile (35 per km²), placing Champaign County #1,066 nationally for density and #62 in Ohio. The median county equivalent has 47 people per square mile; the Ohio median is 120. Put another way, there are about 7.1 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 38,741 | 38,788 | 38,675 | 38,750 | 38,717 | 38,820 |
| Change | — | +47 | −113 | +75 | −33 | +103 |
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 Champaign County
7 incorporated places lie at least partly in Champaign County. Together they are home to 17,276 people (44.5%); the other 21,544 (55.5%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Urbana city, with 11,140 residents in the county. Among places with at least 1,000 residents in 2020, North Lewisburg village grew fastest since then (+1.1%).
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Urbana cityCounty seat | 11,140 | −0.3% | 8.675 |
| St. Paris village | 1,884 | +0.1% | 1.62 |
| Mechanicsburg village | 1,681 | +0.2% | 0.96 |
| North Lewisburg village | 1,657 | +1.1% | 1.08 |
| Christiansburg village | 503 | −1% | 0.238 |
| Woodstock village | 284 | −1% | 0.283 |
| Mutual village | 127 | 0% | 0.135 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Champaign County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Champaign County is a central county of the Urbana, OH Micropolitan Statistical Area. Champaign County is the area’s only county equivalent, so the micro area has the same 429 square miles of land. By combined land it ranks #466 of 542 micropolitan areas, and #337 by population. It belongs to the Dayton-Springfield-Kettering, OH Combined Statistical Area.
ZIP codes
18 ZIP Code Tabulation Areas have land in Champaign County; 9 of them have most of their land inside the county, and the others mainly cover neighboring areas.
430094304443045430474306043070430724307843084433184334343357453124531745344453654538945502
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 Champaign County
Champaign County shares a land border with 6 county equivalents. It has more land than 3 of them. The largest neighbor is Madison County (466.7 mi²) and the smallest is Clark County (395.9 mi²). Together with its neighbors, Champaign County forms a block of 2,996 mi² of land, of which it holds 14.3%.
| Bordering county equivalent | Land mi² | Size vs. Champaign | Compare |
|---|---|---|---|
| Madison County | 466.7 | 1.1× larger | Compare |
| Logan County | 458.5 | 1.1× larger | Compare |
| Union County | 431.7 | about the same | Compare |
| Shelby County | 407.7 | 1.1× smaller | Compare |
| Miami County | 406.6 | 1.1× smaller | Compare |
| Clark County | 395.9 | 1.1× smaller | Compare |
How big is Champaign County compared with U.S. states?
Champaign County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2.4 times as much. Ohio’s county land could hold about 95 areas the size of Champaign County.
Another way to picture it: the same land area would fill a square about 20.7 miles (33.3 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 Champaign County?
Champaign County has more land than 852 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 Champaign County at #2,446 nationally by total area, 76 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 0.2%, compared with a national county-equivalent median of 1.2% — 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 Champaign County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2369 | Warren County, North Carolina | 429.4 | Compare |
| #2370 | Champaign County, Ohio | 429 | This county |
| #2371 | Coffee County, Tennessee | 429 | 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 40.142659, -83.772111. 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: 1,111,045,237 m²; AWATER: 2,180,178 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 Champaign County?
Champaign County, Ohio has 429 square miles (1,111 km²) of land and 0.842 square miles of water, for a total area of 429.8 square miles. It ranks #2370 of 3,222 U.S. county equivalents by land area.
Is Champaign County the largest county in Ohio?
No. Champaign County ranks #47 of 88 in Ohio by land area. The largest is Ashtabula County, with 702.4 square miles of land.
What counties border Champaign County?
Champaign County shares a land border with Clark County, Logan County, Miami County, Union County, Madison County, and Shelby County.
What is the population of Champaign County?
The Census Bureau estimates Champaign County had 38,820 residents on July 1, 2025, ranking #1,236 of 3,222 county equivalents. That is 90 people per square mile of land.
What is the county seat of Champaign County?
The county seat of Champaign County is Urbana.
What cities and towns are in Champaign County?
Champaign County has 7 incorporated places. The most populous five are Urbana city, St. Paris village, Mechanicsburg village, North Lewisburg village, and Christiansburg village; 21,544 residents live outside any incorporated place.
Is Champaign County part of a metropolitan area?
Yes. It is a central county of the Urbana, OH Micropolitan Statistical Area.
How many ZIP codes are in Champaign County?
18 ZIP Code Tabulation Areas have land in Champaign 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 Champaign County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 2.4 times as much land.
How many acres of land are in Champaign County?
The land measurement converts to approximately 274,545 acres. Including water, total area is approximately 275,084 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.