OH · 2026 Census Gazetteer

Ohio counties by area

Official, comparable measurements for 88 counties and county equivalents.

Source fields preservedGEOID · ALAND · AWATER

County equivalents88

Combined land40,859.1 mi²

Combined water3,966.7 mi²

Largest by landAshtabula County

Understanding Ohio’s county areas

The land-area range runs from Lake County at 229.4 mi² to Ashtabula County at 702.4 mi². The largest has 3.1 times the land area of the smallest and accounts for 1.7% of the combined county land in Ohio.

The median county-equivalent land area is 436 mi², below the national median of 604.5 mi². The median describes the middle of the county size distribution; it does not describe how people or development are distributed. A state with a few very large counties can have a much smaller median than its largest entry suggests.

Where water changes the picture

Cuyahoga County has the most assigned water area, at 788.3 mi². Lake County has the highest water share, with water making up 76.6% of its total area. Water area and water percentage answer different questions: the first measures an amount, while the second measures the mix of land and water.

Across all 88 entries, water accounts for 8.8% of the combined total area. This is calculated from the summed land and water measurements, rather than averaging county percentages, which would give each small and large county equal weight.

Compare the largest and smallest county equivalents in Ohio to see land, water, and total area on the same scale.

These calculations use the 2026 Census county records listed below. County-equivalent boundaries vary between states; area alone does not measure population, density, or usable land. See coverage and calculation rules.

Complete area table

Sorted from largest to smallest land area.

#	County / equivalent	Land	Water	Water share
1	Ashtabula CountyGEOID 39007	702.4 mi²	665.8 mi²	48.7%
2	Ross CountyGEOID 39141	689.2 mi²	3.9 mi²	0.6%
3	Licking CountyGEOID 39089	682.4 mi²	4.9 mi²	0.7%
4	Muskingum CountyGEOID 39119	664.5 mi²	8 mi²	1.2%
5	Washington CountyGEOID 39167	632.3 mi²	8 mi²	1.2%
6	Trumbull CountyGEOID 39155	617.6 mi²	18.4 mi²	2.9%
7	Wood CountyGEOID 39173	617.2 mi²	3.4 mi²	0.5%
8	Scioto CountyGEOID 39145	610.2 mi²	6.2 mi²	1%
9	Darke CountyGEOID 39037	598.1 mi²	1.6 mi²	0.3%
10	Adams CountyGEOID 39001	583.9 mi²	2.4 mi²	0.4%
11	Stark CountyGEOID 39151	574.9 mi²	5.3 mi²	0.9%
12	Tuscarawas CountyGEOID 39157	567.6 mi²	4 mi²	0.7%
13	Coshocton CountyGEOID 39031	563.9 mi²	3.5 mi²	0.6%
14	Wayne CountyGEOID 39169	555 mi²	1.9 mi²	0.3%
15	Highland CountyGEOID 39071	553.1 mi²	4.7 mi²	0.8%
16	Seneca CountyGEOID 39147	551 mi²	1.8 mi²	0.3%
17	Franklin CountyGEOID 39049	532.4 mi²	11.2 mi²	2.1%
18	Belmont CountyGEOID 39013	532.2 mi²	9.1 mi²	1.7%
19	Columbiana CountyGEOID 39029	531.9 mi²	2.8 mi²	0.5%
20	Hancock CountyGEOID 39063	531.3 mi²	2.3 mi²	0.4%
21	Knox CountyGEOID 39083	525.5 mi²	4.1 mi²	0.8%
22	Guernsey CountyGEOID 39059	522.2 mi²	6 mi²	1.1%
23	Fairfield CountyGEOID 39045	504.4 mi²	4.2 mi²	0.8%
24	Athens CountyGEOID 39009	504.1 mi²	4.8 mi²	0.9%
25	Pickaway CountyGEOID 39129	501.3 mi²	5.3 mi²	1%
26	Richland CountyGEOID 39139	495.2 mi²	4.8 mi²	1%
27	Huron CountyGEOID 39077	492.2 mi²	3.3 mi²	0.7%
28	Lorain CountyGEOID 39093	490.5 mi²	432.2 mi²	46.8%
29	Brown CountyGEOID 39015	489.6 mi²	3.4 mi²	0.7%
30	Portage CountyGEOID 39133	487.5 mi²	16.6 mi²	3.3%
31	Putnam CountyGEOID 39137	482.5 mi²	1.8 mi²	0.4%
32	Hardin CountyGEOID 39065	470.3 mi²	0.2 mi²	0.1%
33	Madison CountyGEOID 39097	466.7 mi²	0.8 mi²	0.2%
34	Butler CountyGEOID 39017	466.5 mi²	3.5 mi²	0.8%
35	Gallia CountyGEOID 39053	466.5 mi²	4.7 mi²	1%
36	Mercer CountyGEOID 39107	462.4 mi²	11 mi²	2.3%
37	Montgomery CountyGEOID 39113	461.4 mi²	2.9 mi²	0.6%
38	Logan CountyGEOID 39091	458.5 mi²	8.3 mi²	1.8%
39	Cuyahoga CountyGEOID 39035	457.2 mi²	788.3 mi²	63.3%
40	Monroe CountyGEOID 39111	455.6 mi²	1.7 mi²	0.4%
41	Lawrence CountyGEOID 39087	453.4 mi²	3.9 mi²	0.8%
42	Clermont CountyGEOID 39025	452.6 mi²	7.7 mi²	1.7%
43	Delaware CountyGEOID 39041	443.1 mi²	14.2 mi²	3.1%
44	Pike CountyGEOID 39131	440.3 mi²	3.7 mi²	0.8%
45	Union CountyGEOID 39159	431.7 mi²	5.2 mi²	1.2%
46	Meigs CountyGEOID 39105	429.5 mi²	2.9 mi²	0.7%
47	Champaign CountyGEOID 39021	429 mi²	0.8 mi²	0.2%
48	Preble CountyGEOID 39135	424.2 mi²	2.3 mi²	0.5%
49	Ashland CountyGEOID 39005	423 mi²	3.8 mi²	0.9%
50	Holmes CountyGEOID 39075	422.6 mi²	1.4 mi²	0.3%
51	Medina CountyGEOID 39103	421.5 mi²	1.6 mi²	0.4%
52	Hocking CountyGEOID 39073	421.4 mi²	2.3 mi²	0.5%
53	Williams CountyGEOID 39171	420.7 mi²	2.4 mi²	0.6%
54	Jackson CountyGEOID 39079	420.3 mi²	1.2 mi²	0.3%
55	Paulding CountyGEOID 39125	416.4 mi²	2.4 mi²	0.6%
56	Morgan CountyGEOID 39115	416.4 mi²	5.4 mi²	1.3%
57	Henry CountyGEOID 39069	416 mi²	3.7 mi²	0.9%
58	Greene CountyGEOID 39057	413.6 mi²	2.6 mi²	0.6%
59	Summit CountyGEOID 39153	412.7 mi²	7.3 mi²	1.7%
60	Vinton CountyGEOID 39163	412.3 mi²	2.6 mi²	0.6%
61	Mahoning CountyGEOID 39099	411.5 mi²	13.7 mi²	3.2%
62	Defiance CountyGEOID 39039	411.4 mi²	2.7 mi²	0.7%
63	Van Wert CountyGEOID 39161	409.2 mi²	1.3 mi²	0.3%
64	Clinton CountyGEOID 39027	408.7 mi²	3.6 mi²	0.9%
65	Sandusky CountyGEOID 39143	408.2 mi²	9.5 mi²	2.3%
66	Jefferson CountyGEOID 39081	408.1 mi²	2.8 mi²	0.7%
67	Perry CountyGEOID 39127	407.9 mi²	4.5 mi²	1.1%
68	Shelby CountyGEOID 39149	407.7 mi²	3 mi²	0.7%
69	Wyandot CountyGEOID 39175	406.9 mi²	0.7 mi²	0.2%
70	Miami CountyGEOID 39109	406.6 mi²	3.1 mi²	0.7%
71	Fayette CountyGEOID 39047	406.4 mi²	0.7 mi²	0.2%
72	Morrow CountyGEOID 39117	406.1 mi²	1.1 mi²	0.3%
73	Hamilton CountyGEOID 39061	405.5 mi²	7.2 mi²	1.7%
74	Fulton CountyGEOID 39051	405.5 mi²	1.8 mi²	0.4%
75	Marion CountyGEOID 39101	403.8 mi²	0.4 mi²	0.1%
76	Allen CountyGEOID 39003	402.5 mi²	4.3 mi²	1.1%
77	Harrison CountyGEOID 39067	402.3 mi²	8.4 mi²	2.1%
78	Crawford CountyGEOID 39033	401.8 mi²	0.9 mi²	0.2%
79	Warren CountyGEOID 39165	401.4 mi²	6.1 mi²	1.5%
80	Auglaize CountyGEOID 39011	401.4 mi²	0.5 mi²	0.1%
81	Geauga CountyGEOID 39055	400.4 mi²	8 mi²	2%
82	Noble CountyGEOID 39121	398 mi²	6.6 mi²	1.6%
83	Clark CountyGEOID 39023	395.9 mi²	5.6 mi²	1.4%
84	Carroll CountyGEOID 39019	394.7 mi²	4.3 mi²	1.1%
85	Lucas CountyGEOID 39095	339.7 mi²	256.2 mi²	43%
86	Ottawa CountyGEOID 39123	254.7 mi²	330.4 mi²	56.5%
87	Erie CountyGEOID 39043	251.3 mi²	374.5 mi²	59.8%
88	Lake CountyGEOID 39085	229.4 mi²	749.9 mi²	76.6%

How to read this table. Land and water areas are Census statistical measurements in square miles. Adding county rows can differ slightly from separately published state totals because of rounding and geographic treatment.