Hamilton County, Indiana
County seat: Noblesville · Population 387,036 (2025) · 394 sq mi
Hamilton County is the 4th most populous of Indiana's 92 counties, with 387,036 people (2025 estimate). Its county seat is Noblesville. It is part of the Central (Region 5) region, one of the 12 Indiana economic growth regions (DWD / WorkOne regions). The map shows its 8 cities and towns and the 6 neighboring counties.
Hamilton County facts
- County seat
- Noblesville
- Population (2025 estimate)
- 387,036 +11.4% since 2020
- Land area
- 394 sq mi 50th largest of 92
- Water area
- 8 sq mi
- Population density
- 981 per sq mi
- Established
- 1823
- Named after
- Alexander Hamilton American Founding Father and statesman (1755/1757–1804)
- Largest city
- Carmel 105,634
- Median household income
- $121,530
- Cities and towns
- 8 plus 3 CDPs
- ZIP codes
- 23
- Time zone
- Eastern
- FIPS code
- 18057
Cities and towns in Hamilton County
Hamilton County has 8 incorporated cities, towns and villages. Populations count the people living inside Hamilton County; cities that cross a county line also list the other counties.
| Name | Type | Population 2025 | Also in |
|---|---|---|---|
| Carmel | City | 105,634 | |
| Fishers | City | 104,812 | |
| Noblesville (county seat) | City | 76,111 | |
| Westfield | City | 66,258 | |
| Sheridan | Town | 5,746 | |
| Cicero | Town | 5,581 | |
| Arcadia | Town | 1,458 | |
| Atlanta | Town | 731 |
Unincorporated communities (CDPs)
Census-designated places are communities without their own city government; the county provides their services.
| Community | Population | Also in |
|---|---|---|
| Hortonville | 229 | |
| Riverwood | 87 | |
| Fishersburg | 28 | Madison County |
ZIP codes in Hamilton County
23 ZIP codes reach into Hamilton County. ZIP codes ignore county lines, so some also cover a neighboring county.
- 46030
- 46031 also Tipton County
- 46032
- 46033
- 46034
- 46037
- 46038
- 46040 also Hancock and Madison counties
- 46050 also Clinton, Boone and Tipton counties
- 46055 also Hancock County
- 46060 also Madison County
- 46062
- 46069 also Boone and Clinton counties
- 46074
- 46077 also Boone and Marion counties
- 46236 also Marion and Hancock counties
- 46240 also Marion County
- 46250 also Marion County
- 46256 also Marion County
- 46260 also Marion County
- 46268 also Marion and Boone counties
- 46280
- 46290
Population of Hamilton County, 2020–2025
Hamilton County grew by 39,546 people (+11.4%) between April 2020 and July 2025: 8,044 more births than deaths and a net gain of 31,594 people from migration.
| Year (July 1) | Population |
|---|---|
| 2020 | 349,011 |
| 2021 | 357,542 |
| 2022 | 366,036 |
| 2023 | 372,450 |
| 2024 | 379,685 |
| 2025 | 387,036 |
Neighboring counties
- Tipton County north · 15,319 people
- Madison County northeast · 135,088 people
- Boone County west · 80,689 people
- Marion County south · 992,196 people
- Hancock County southeast · 90,969 people
- Clinton County northwest · 33,322 people
Printable Hamilton County map
The PDF is a vector file with real text: it prints sharp on Letter paper and you can search it for a town. The PNG is 2400 pixels wide for slides and documents. Both are free to use with a credit to WhichCounty.
- PDF (Letter) (93 KB)
- PNG (2400 px) (66 KB)
Paste this code to embed the map on your site:
Sources
- Boundaries: U.S. Census Bureau, 2025 Cartographic Boundary Files (1:500,000).
- Population: Census Bureau county and city estimates, Vintage 2025. CDP populations: American Community Survey 2020–2024.
- Places and ZIP codes: Census Bureau 2026 Gazetteer and 2020 ZIP Code Tabulation Area relationship files.
- County seat, founding year and name origin: Wikidata (CC0), checked against state sources.
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