County outline
Where Seminole County is located
Area breakdown
Land accounts for 89.6% of Seminole County’s measured area and water for 10.4%. Its combined area converts to 894.4 square kilometers or approximately 221,017 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 309.39 | 801.316 | 198,009.6 |
| Water | 35.949 | 93.107 | 23,007.4 |
| Total | 345.339 | 894.424 | 221,017 |
How Seminole County compares
By original Census land area, Seminole County ranks #64 of 67 in Florida and #2786 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.444 times the Florida county-equivalent median of 696.5 square miles. It accounts for 0.6% of the combined county land area in the state.
See the complete Florida ranking · What counts as a county equivalent?
Population and density of Seminole County
The Census Bureau estimates that 491,884 people lived in Seminole County on July 1, 2025. That ranks #151 of 3,222 county equivalents nationally and #13 of 67 in Florida. Since the April 1, 2020 estimates base of 470,856, the population has grown by 21,028 (+4.5%), compared with +8.9% for Florida as a whole.
With 309.4 square miles of land, that is 1,590 people per square mile (614 per km²), placing Seminole County #110 nationally for density and #4 in Florida. The median county equivalent has 47 people per square mile; the Florida median is 209. Put another way, there are about 0.403 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 471,471 | 471,040 | 480,635 | 487,504 | 489,664 | 491,884 |
| Change | — | −431 | +9,595 | +6,869 | +2,160 | +2,220 |
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 Seminole County
7 incorporated places lie at least partly in Seminole County. Together they are home to 261,938 people (53.3%); the other 229,946 (46.7%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Sanford city, with 67,483 residents in the county. Among places with at least 1,000 residents in 2020, Longwood city grew fastest since then (+11.9%).
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Sanford cityCounty seat | 67,483 | +10.3% | 24.1 |
| Altamonte Springs city | 48,000 | +3.8% | 9.139 |
| Oviedo city | 41,317 | +3.2% | 15.5 |
| Winter Springs city | 39,585 | +3.2% | 14.9 |
| Casselberry city | 31,872 | +10.2% | 7.085 |
| Longwood city | 16,892 | +11.9% | 5.527 |
| Lake Mary city | 16,789 | −0.3% | 9.078 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Seminole County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Seminole County is a central county of the Orlando-Kissimmee-Sanford, FL Metropolitan Statistical Area. Its 4 county equivalents have 2,957,672 residents on 3,493.8 square miles of land; Seminole County accounts for 8.9% of the land and 16.6% of the residents. By combined land it ranks #82 of 393 metropolitan areas, and #20 by population. It belongs to the Orlando-Lakeland-Deltona, FL Combined Statistical Area.
| County equivalent | Population 2025 | Land mi² |
|---|---|---|
| Orange County | 1,528,002 | 903 |
| Seminole County | 491,884 | 309.4 |
| Osceola County | 481,718 | 1,327.3 |
| Lake County | 456,068 | 954 |
ZIP codes
17 ZIP Code Tabulation Areas have land in Seminole County; 14 of them have most of their land inside the county, and the others mainly cover neighboring areas.
3270132703327073270832714327303273232746327503275132765327663277132773327793279232810
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 Seminole County
Seminole County shares a land border with 3 county equivalents. Each of them has more land than Seminole County. The largest neighbor is Volusia County (1,101.3 mi²) and the smallest is Orange County (903 mi²). Together with its neighbors, Seminole County forms a block of 3,267.7 mi² of land, of which it holds 9.5%.
| Bordering county equivalent | Land mi² | Size vs. Seminole | Compare |
|---|---|---|---|
| Volusia County | 1,101.3 | 3.6× larger | Compare |
| Lake County | 954 | 3.1× larger | Compare |
| Orange County | 903 | 2.9× larger | Compare |
How big is Seminole County compared with U.S. states?
Seminole County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 3.3 times as much. Florida’s county land could hold about 173 areas the size of Seminole County.
Another way to picture it: the same land area would fill a square about 17.6 miles (28.3 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 Seminole County?
Seminole County has more land than 436 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 Seminole County at #2,744 nationally by total area, 42 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.
Its water share is 10.4%, compared with a national county-equivalent median of 1.2% — 9.2 percentage points higher. 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 Seminole County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2785 | Page County, Virginia | 310 | Compare |
| #2786 | Seminole County, Florida | 309.4 | This county |
| #2787 | Middlesex County, New Jersey | 309.3 | 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 28.689944, -81.132626. 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: 801,317,561 m²; AWATER: 93,106,501 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 Seminole County?
Seminole County, Florida has 309.4 square miles (801.3 km²) of land and 35.9 square miles of water, for a total area of 345.3 square miles. It ranks #2786 of 3,222 U.S. county equivalents by land area.
Is Seminole County the largest county in Florida?
No. Seminole County ranks #64 of 67 in Florida by land area. The largest is Collier County, with 1,997 square miles of land.
What counties border Seminole County?
Seminole County shares a land border with Orange County, Volusia County, and Lake County.
What is the population of Seminole County?
The Census Bureau estimates Seminole County had 491,884 residents on July 1, 2025, ranking #151 of 3,222 county equivalents. That is 1,590 people per square mile of land.
What is the county seat of Seminole County?
The county seat of Seminole County is Sanford.
What cities and towns are in Seminole County?
Seminole County has 7 incorporated places. The most populous five are Sanford city, Altamonte Springs city, Oviedo city, Winter Springs city, and Casselberry city; 229,946 residents live outside any incorporated place.
Is Seminole County part of a metropolitan area?
Yes. It is a central county of the Orlando-Kissimmee-Sanford, FL Metropolitan Statistical Area, which has 4 county equivalents and 2,957,672 residents.
How many ZIP codes are in Seminole County?
17 ZIP Code Tabulation Areas have land in Seminole County, and 14 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Seminole County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 3.3 times as much land.
How many acres of land are in Seminole County?
The land measurement converts to approximately 198,010 acres. Including water, total area is approximately 221,017 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.