County facts · Land area · October 21, 2026
Largest Counties in Ohio by Area and Population
The largest Ohio counties by land area and by 2023 population, plus the smallest, county seats and a link to each official parcel map.
Looking for the largest counties in Ohio? Ohio has 88 counties covering about 40,859 square miles of land, based on the Census Bureau's 2020 Gazetteer. The largest by land area is Ashtabula County, at about 702 square miles, roughly 3.1 times the size of the smallest, Lake County (229 sq mi). Measured by people instead, the largest is Franklin County, with about 1,326,063 residents in the Census Bureau's July 1, 2023 estimate.
The tables below rank the counties both ways. Each row links to the county's Platbookmapper page and straight to its official parcel viewer.
Ohio counties at a glance
- Counties: 88
- Land area: about 40,859 sq mi, plus about 3,967 sq mi of water inside county lines
- Residents, 2023 estimates: about 11,785,935, or about 288 people per square mile of land
- Median county land area: about 436 sq mi
- With a verified public parcel viewer in our directory: 87 of 88 (15 of them through a statewide viewer)
The 10 largest Ohio counties by land area
| # | County | Seat | Land (sq mi) | 2023 pop. | People per sq mi | Parcel viewer |
|---|---|---|---|---|---|---|
| 1 | Ashtabula County | Jefferson | 702 | 96,845 | 138 | county web map |
| 2 | Ross County | Chillicothe | 689 | 76,501 | 111 | Ohio Statewide Parcels layer in ArcGIS Map Viewer |
| 3 | Licking County | Newark | 682 | 183,201 | 268 | county web map |
| 4 | Muskingum County | Zanesville | 665 | 86,305 | 130 | county web map |
| 5 | Washington County | Marietta | 632 | 58,577 | 93 | Ohio Statewide Parcels layer in ArcGIS Map Viewer |
| 6 | Trumbull County | Warren | 618 | 200,373 | 324 | Beacon (Schneider Geospatial) |
| 7 | Wood County | Bowling Green | 617 | 132,650 | 215 | Beacon (Schneider Geospatial) |
| 8 | Scioto County | Portsmouth | 610 | 71,969 | 118 | Ohio Statewide Parcels layer in ArcGIS Map Viewer |
| 9 | Darke County | Greenville | 598 | 51,415 | 86 | Ohio Statewide Parcels layer in ArcGIS Map Viewer |
| 10 | Adams County | West Union | 584 | 27,521 | 47 | Beacon (Schneider Geospatial) |
Together these 10 cover about 16% of Ohio's land area and hold about 8% of its residents.
The 10 most populous Ohio counties
| # | County | Seat | 2023 pop. | Land (sq mi) | Parcel viewer |
|---|---|---|---|---|---|
| 1 | Franklin County | Columbus | 1,326,063 | 532 | county web map |
| 2 | Cuyahoga County | Cleveland | 1,233,088 | 457 | county web map |
| 3 | Hamilton County | Cincinnati | 827,058 | 405 | ArcGIS Experience Builder |
| 4 | Summit County | Akron | 535,733 | 413 | county web map |
| 5 | Montgomery County | Dayton | 533,796 | 461 | county web map |
| 6 | Lucas County | Toledo | 425,484 | 340 | county web map |
| 7 | Butler County | Hamilton | 393,043 | 467 | listed link under review |
| 8 | Stark County | Canton | 372,716 | 575 | ArcGIS Web AppBuilder |
| 9 | Lorain County | Elyria | 317,910 | 491 | ArcGIS Experience Builder |
| 10 | Warren County | Lebanon | 252,148 | 401 | Ohio Statewide Parcels layer in ArcGIS Map Viewer |
These 10 hold about 53% of Ohio's residents in the 2023 estimates.
The 5 smallest Ohio counties by land area
| County | Seat | Land (sq mi) | 2023 pop. | Parcel viewer |
|---|---|---|---|---|
| Lake County | Painesville | 229 | 231,640 | ArcGIS Experience Builder |
| Erie County | Sandusky | 251 | 74,035 | Beacon (Schneider Geospatial) |
| Ottawa County | Port Clinton | 255 | 39,803 | Beacon (Schneider Geospatial) |
| Lucas County | Toledo | 340 | 425,484 | county web map |
| Carroll County | Carrollton | 395 | 26,758 | county web map |
Most and least crowded
- Most people per square mile: Cuyahoga County, about 2,697 (then Franklin County, 2,491, and Hamilton County, 2,040)
- Fewest people per square mile: Monroe County, about 29 (then Vinton County, 30, and Morgan County, 33)
Counties with the most water
The Census Bureau reports water separately from land. It counts lakes, reservoirs, rivers and, for coastal and Great Lakes counties, the water inside the county boundary.
- Cuyahoga County: about 788 sq mi of water, 63% of its total area
- Lake County: about 750 sq mi of water, 77% of its total area
- Ashtabula County: about 666 sq mi of water, 49% of its total area
Using these numbers in a land search
- Land area is not parcel count. A large rural county can hold fewer parcels than a small suburban one, so size alone says little about how busy its parcel map is.
- Search, don't scroll. In a big county, type an address, owner name or parcel number into the viewer's search box, where it has one, instead of panning across the map.
- Records follow the county line. Deeds, plats and tax bills are kept by the county where the parcel sits, so a tract that crosses a county line usually has a parcel number in each county.
- Rounded figures. Land and water areas are rounded to whole square miles. People per square mile is the 2023 estimate divided by land area.
Related guides
- Ohio county GIS websites by viewer
- Ohio plat maps
- Ohio parcel map guide
- Ohio landowner maps for hunting
- Indiana–Ohio border counties
- Kentucky–Ohio border counties
- Ohio–West Virginia border counties
More: All Ohio counties on Platbookmapper
Sources
- U.S. Census Bureau Gazetteer files, 2020 county land and water area.
- U.S. Census Bureau, Population Estimates Program, county totals, Vintage 2023 (July 1, 2023 estimates)
- Platbookmapper county GIS directory (live data file behind our county pages, pulled October 21, 2026) for each county's official parcel viewer.
- County seats: Wikidata (county seat property), cross-checked against Census place names.